CASTLE BIOSCIENCES INC 10-K

Item 9A. Controls and Procedures. Evaluation of Disclosure Controls and Procedures We maintain “disclosure controls and procedures,” as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act, that are designed to ensure that information required to be disclosed in the reports that we file or submit under the Exchange Act is (1) recorded, processed, summarized and reported, within the time periods specified in the SEC’s rules and forms and (2) accumulated and communicated to our management, including our principal executive officer and principal financial officer, to allow timely decisions regarding required disclosure. Management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures. Our management, with the participation of our Chief Executive Officer and Chief Financial Officer, evaluated the effectiveness of our disclosure controls and procedures as of December 31, 2025. Based upon the evaluation, our Chief Executive Officer and Chief Financial Officer concluded that, as of December 31, 2025, our disclosure controls and procedures were effective at the reasonable assurance level. Management’s Report on Internal Control over Financial Reporting Our management is responsible for establishing and maintaining adequate internal control over financial reporting as such term as defined in Exchange Act Rule 13a-15(f). Internal control over financial reporting is a process designed by, or under the supervision of, our principal executive officer and principal financial officer, and effected by our board of directors, management and other personnel, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of consolidated financial statements for external purposes in accordance with U.S. GAAP. As of December 31, 2025, our management assessed the effectiveness of our internal control over financial reporting using the criteria set forth by the Committee of Sponsoring Organizations of the Treadway Commission in Internal Control-Integrated Framework (2013 Framework) . Based on this assessment, our management concluded that, as of December 31, 2025, our internal control over financial reporting was effective based on those criteria. Our independent registered public accounting firm, KPMG LLP, has audited the effectiveness of our internal control over financial reporting as of December 31, 2025, as stated in its attestation report contained in Item 15 of this Annual Report on Form 10-K. Changes in Internal Control over Financial Reporting There have been no changes in our internal control over financial reporting (as defined in Rules 13a-15(f) or 15d-15(f) under the Exchange Act) that occurred during the fourth quarter of 2025 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting. 103 Table of Contents Item 9B. Other Information. Securities Trading Plans of Directors and Executive Officers On November 13, 2025 , Frank Stokes , our Chief Financial Officer , adopted a Rule 10b5-1 trading arrangement providing for the sale from time to time of 13,001 shares of our common stock. The trading arrangement is intended to satisfy the affirmative defense in Rule 10b5-1(c). The duration of the trading arrangement is estimated to be from February 27, 2026 until the earlier of all transaction under the trading arrangement being completed or March 31, 2026 . On December 3, 2025 , Derek Maetzold , our Chief Executive Officer , adopted a Rule 10b5-1 trading arrangement providing for the sale from time to time of an aggregate of up to 252,800 shares of our common stock and up to 100% of the shares of our common stock issued upon the settlement of 121,316 shares of RSUs and PSUs, less the number of shares withheld to cover tax withholding obligations in connection with the vesting and settlement of such RSUs and PSUs. The trading arrangement is intended to satisfy the affirmative defense in Rule 10b5-1(c). The duration of the trading arrangement is estimated to be from March 11, 2026 until the earlier of all transaction under the trading arrangement being completed or August 31, 2026 . On December 10, 2025 , Tobin Juvenal , our Chief Commercial Officer , adopted a Rule 10b5-1 trading arrangement providing for the sale from time to time of an aggregate of up to 45,000 shares of our common stock and up to 100% of the shares of our common stock issued upon the settlement of 34,978 shares of RSUs and PSUs, less the number of shares withheld to cover tax withholding obligations in connection with the vesting and settlement of such RSUs and PSUs. The trading arrangement is intended to satisfy the affirmative defense in Rule 10b5-1(c). The duration of the trading arrangement is estimated to be from March 12, 2026 until the earlier of all transaction under the trading arrangement being completed or September 4, 2026 . No other officers or directors, as defined in Rule 16a-1(f), adopted and/or terminated a Rule 10b5-1 trading arrangement or a non-Rule 10b5-1 trading arrangement, as defined in Regulation S-K Item 408, during the last fiscal quarter. Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections. Not applicable. 104 Table of Contents PART III Certain information required by Part III is omitted from this Annual Report on Form 10-K since we intend to file our definitive proxy statement for our 2026 Annual Meeting of Stockholders (the “Proxy Statement”) pursuant to Regulation 14A of the Exchange Act, not later than 120 days after the end of the fiscal year covered by this Annual Report on Form 10-K, and certain information to be included in the Proxy Statement is incorporated herein by reference. Item 10. Directors, Executive Officers and Corporate Governance. The information required by this item is to be included in the Proxy Statement as follows: • The information relating to our executive officers is to be included in the section entitled “Executive Officers,” • The information relating to our directors and nominees for director is to be included in the section entitled “Proposal 1: Election of Directors,” • The information relating to our audit committee and audit committee financial expert is to be included in the section entitled “Information Regarding the Board of Directors and Corporate Governance,” and • If required, the information regarding delinquent reports under Section 16(a) of the Exchange Act is to be included in the section entitled “Delinquent Section 16(a) Reports.” Such information is to be included in the Proxy Statement and is incorporated herein by reference. The information required by Item 408(b) of Regulation S-K will be set forth in the section captioned “ Insider Trading Policy; Prohibition on Hedging, Short Sales and Pledging ” in our Proxy Statement and is incorporated herein by reference. We have adopted a written Code of Business Conduct and Ethics (“Ethics Code”) that applies to all officers, directors and employees, including our principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions. The Ethics Code is available on our website at www.CastleBiosciences.com. If we ever were to amend or waive any provision that applies to our principal executive officer, principal financial officer, principal accounting officer or controller, or any person performing similar functions, we intend to satisfy our required disclosure obligations, if any, with respect to any such waiver or amendment by posting such information on our website, rather than by filing a Current Report on Form 8-K. Information found on, or accessible through, our website is not part of, and is not incorporated into, this Annual Report on Form 10-K. Item 11. Executive Compensation. The information required by this item is to be included in the Proxy Statement under the sections entitled “Compensation Discussion and Analysis,” “Executive Compensation Tables,” “Director Compensation,” “Compensation Committee Interlocks and Insider Participation,” and “Compensation Committee Report” and is incorporated herein by reference, provided that the information required by Item 402(x) of Regulation S-K shall be set forth in the section entitled “Policies and practices related to the grant of certain equity awards close in time to the release of material nonpublic information” in the Proxy Statement and is incorporated herein by reference. Information disclosed therein pursuant to Item 402(v) of Regulation S-K relating to pay versus performance will not be incorporated herein by reference. Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters. The information required by this item with respect to equity compensation plans is to be included in the Proxy Statement under the section entitled “Equity Compensation Plan Information” and the information required by this item with respect to security ownership of certain beneficial owners and management is to be included in the Proxy Statement under the section entitled “Security Ownership of Certain Beneficial Owners and Management” and in each case is incorporated herein by reference. 105 Table of Contents Item 13. Certain Relationships and Related Transactions, and Director Independence. The information required by this item is to be included in the Proxy Statement under the sections entitled “Transactions with Related Persons and Indemnifications—Related Person Transactions Policy and Procedures” and “Information Regarding the Board of Directors and Corporate Governance” and is incorporated herein by reference. Item 14. Principal Accountant Fees and Services. Our independent registered public accounting firm is KPMG LLP , Houston, TX , PCAOB ID: 185 . The information required by this item is to be included in the Proxy Statement under the section entitled “Proposal 2: Ratification of Selection of Independent Registered Public Accounting Firm” and is incorporated herein by reference. 106 Table of Contents PART IV Item 15. Exhibit and Financial Statement Schedules. (a)(1) Financial Statements. The consolidated financial statements and supplementary data required by this item are included after the Signature page of this Annual Report on Form 10-K beginning on page F-1 . (a)(2) Financial Statement Schedules. All schedules have been omitted because they are not required or because the required information is given in the Consolidated Financial Statements or Notes thereto. (a)(3) Exhibits. The exhibits listed in the Exhibit Index below are filed or incorporated by reference as part of this Annual Report on Form 10-K. Exhibit Index Exhibit Number Description of document 3.1 Amended and Restated Certificate of Incorporation of the Registrant, incorporated by reference to Exhibit 3.1 of the Registrant’s Current Report on Form 8-K filed with the SEC on May 23, 2025. 3.2 Amended and Restated Bylaws of the Registrant, incorporated by reference to Exhibit 3. 1 of the Registrant’s Current Report on Form 8-K filed with the SEC on August 8, 2025 . 4.1 Description of securities registered under Section 12 of the Exchange Act, incorporated by reference to Exhibit 4.1 of the Registrant's Annual Report on Form 10-K filed with the SEC on March 10, 2020. 4.2 Form of Common Stock Certificate of the Registrant, incorporated by reference to Exhibit 4.1 of the Registrant’s Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on June 26, 2019. Equity Compensation Plans 10.1+ Castle Biosciences, Inc. 2008 Stock Plan, incorporated by reference to Exhibit 10.2 of the Registrant’s Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on June 26, 2019. 10.2+ Forms of Stock Option Agreement, Exercise Notice and Investment Representation Statement under the 2008 Stock Plan, incorporated by reference to Exhibit 10.3 of the Registrant’s Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on June 26, 2019. 10.3+ Castle Biosciences, Inc. 2018 Equity Incentive Plan, as amended, incorporated by reference to Exhibit 10.4 of the Registrant’s Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on June 26, 2019. 10.4+ Forms of Stock Option Grant Notice, Option Agreement and Notice of Exercise under the 2018 Equity Incentive Plan, incorporated by reference to Exhibit 10.5 of the Registrant’s Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on June 26, 2019. 10.5+ Castle Biosciences, Inc. 2019 Equity Incentive Plan, incorporated by reference to Exhibit 99.3 of the Registrant’s Registration Statement on Form S-8 (File No. 333-232884), originally filed with the SEC on July 29, 2019. 10.6+ Forms of Stock Option Grant Notice, Option Agreement and Notice of Exercise under the 2019 Equity Incentive Plan, incorporated by reference to Exhibit 10.7 of the Registrant’s Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on June 26, 2019. 10.7+ Forms of Restricted Stock Unit Grant Notice and Restricted Stock Unit Award Agreement under the 2019 Equity Incentive Plan, incorporated by reference to Exhibit 10.1 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on November 9, 2020. 10.8+ Castle Biosciences, Inc. 2019 Employee Stock Purchase Plan, incorporated by reference to Exhibit 10.8 of the Registrant’s Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on June 26, 2019. 10.9+ Castle Biosciences, Inc. 2022 Inducement Plan, as amended and restated, incorporated by reference to Exhibit 10.2 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on No vember 3, 2025 . 107 Table of Contents Exhibit Number Description of document 10.10+ Forms of Restricted Stock Unit Grant Notice and Restricted Stock Unit Award Agreement under the Castle Biosciences, Inc. 2022 Inducement Plan, incorporated by reference to Exhibit 10.12 of the Registrant ’ s Annual Report on Form 10-K filed with the SEC on February 28, 2023. 10.11+ Forms of Stock Option Grant Notice, Option Agreement and Notice of Exercise under the Castle Biosciences, Inc. 2022 Inducement Plan, incorporated by reference to Exhibit 10.13 of the Registrant ’ s Annual Report on Form 10-K filed with the SEC on February 28, 2023. Agreements with Executive Officers and Directors 10.12+ Form of Indemnity Agreement by and between the Registrant and its directors and officers, incorporated by reference to Exhibit 10.1 of the Registrant’s Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on June 26, 2019. 10.13+ Form of Director Agreement by and between the Registrant and certain of its directors, incorporated by reference to Exhibit 10.9 of the Registrant’s Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on June 26, 2019. 10.14+ Non-Employee Director Compensation Policy, as amended , incorporated by reference to Exhibit 10. 1 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on November 3 , 2025. 10.15+ Amended and Restated Executive Employment Agreement, dated September 20, 2012, as amended, by and between the Registrant and Derek J. Maetzold, incorporated by reference to Exhibit 10.10 of the Registrant’s Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on June 26, 2019. 10.16+ Offer Letter Agreement, dated November 9, 2017, by and between the Registrant and Frank Stokes, incorporated by reference to Exhibit 10.13 of the Registrant’s Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on June 26, 2019. 10.17+ Executive Employment Agreement, dated September 15, 2008, as amended, by and between the Registrant and Kristen Oelschlager, incorporated by reference to Exhibit 10.2 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on May 10, 2021. 10.18+ Executive Employment Agreement, dated October 1, 2008, as amended, by and between the Registrant and Tob y Juvenal, incorporated by reference to Exhibit 10.3 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on May 10, 2021. 10.19+ Castle Biosciences, Inc. Retirement Policy, incorporated by reference to Exhibit 10.16 of the Registrant ’ s Annual Report on Form 10-K filed with the SEC on February 28, 2023. 10.20+† Castle Biosciences, Inc. Severance and Change in Control Plan, incorporated by reference to Exhibit 10.20 of the Registrant ’ s Annual Report on Form 10-K filed with the SEC on February 28, 2024. 10.21+ Amended Participation Agreement, dated June 20, 2025 by and between the Registrant and Toby Juvenal, incorporated by reference to Exhibit 10.6 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on August 4, 2025 . 10.22+ Amended Participation Agreement, dated June 20, 2025 by and between the Registrant and Kristen Oelschlager, incorporated by reference to Exhibit 10.7 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on August 4, 2025. 10.23+ Amended Participation Agreement, dated April 2, 2024, by and between the Company and Derek Maetzold, incorporated by reference to Exhibit 10.5 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on May 2, 2024. 10.24+ Amended Participation Agreement, dated June 20, 2025 by and between the Registrant and Frank Stokes, incorporated by reference to Exhibit 10.5 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on August 4, 2025. Lease Agreements 10.25 Standard Office Lease, dated as of October 5, 2015, by and between the Registrant and Merced Restart Phoenix Investors II, LLC, incorporated by reference to Exhibit 10.14 of the Registrant’s Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on June 26, 2019. 10.26 First Amendment to Lease, dated December 4, 2018, by and between the Registrant and Alturas Siete I, LLC, incorporated by reference to Exhibit 10.15 of the Registrant ’ s Annual Report on Form 10-K, filed with the SEC on March 10, 2020. 10.27 Second Amendment to Standard Office Lease, dated December 16, 2019, by and between the Registrant and Alturas Siete I, LLC, incorporated by reference to Exhibit 10.2 of the Registrant’s Current Report on Form 8-K filed with the SEC on December 19, 2019. 108 Table of Contents Exhibit Number Description of document 10.28 Third Amendment to Standard Office Lease, dated November 29, 2021, by and between the Company and Alturas Siete, I, LLC, incorporated by reference to Exhibit 10.2 of the Registrant’s Current Report on Form 8-K filed with the SEC on December 3, 2021. 10.29† Fourth Amendment to Standard Office Lease, dated March 11, 2022, by and between the Registrant and Alturas Siete I, LLC, incorporated by reference to Exhibit 10.1 of the Registrant’s Current Report on Form 8-K filed with the SEC on March 17, 2022. 10.30† Fifth Amendment to Standard Office Lease, dated October 24, 2022, by and between the Registrant and Alturas Siete I, LLC, incorporated by reference to Exhibit 10.25 of the Registrant’s Current Report on Form 10-K filed with the SEC on February 28, 2023. 10.31 Standard Office Lease, dated December 16, 2019, by and between the Registrant and Alturas Siete, II, LLC, incorporated by reference to Exhibit 10.1 of the Registrant’s Current Report on Form 8-K filed with the SEC on December 19, 2019. 10.32 First Amendment to Standard Office Lease, dated February 16, 2021, by and between the Registrant and Alturas Siete II, LLC, incorporated by reference to Exhibit 10.1 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on May 10, 2021. 10.33 Second Amendment to Standard Office Lease, dated November 29, 2021, by and between the Company and Alturas Siete, II, LLC, incorporated by reference to Exhibit 10.1 of the Registrant’s Current Report on Form 8-K filed with the SEC on December 3, 2021. 10.34 Third Amendment to Standard Office Lease, dated February 9, 2023, by and between the Registrant and Alturas Siete, II, LLC, incorporated by reference to Exhibit 10.29 of the Registrant’s Annual Report on Form 10-K filed with the SEC on February 28, 2023. 10.35 Fourth Amendment to Standard Office Lease, dated April 18, 2023 by and between the Registrant and Alturas Siete II, LLC, incorporated by reference to Exhibit 10.4 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on May 10 2023. 10.36 Commercial Lease, dated December 17, 2019, by and between the Registrant and Tannos Land Holding III, LLC, incorporated by reference to Exhibit 10.3 of the Registrant’s Current Report on Form 8-K filed with the SEC on December 19, 2019. 10.37 First Amendment to Commercial Lease, dated November 13, 2020, by and between the Registrant and Tannos Land Holdings III, LLC, incorporated by reference to Exhibit 10.23 of the Registrant ’ s Annual Report on Form 10-K filed with the SEC on March 11, 2021. 10.38 Second Amendment to Commercial Lease, executed December 15, 2022, by and between the Registrant and Tannos Land Holdings III, LLC, incorporated by reference to Exhibit 10.32 of the Registrant ’ s Annual Report on Form 10-K filed with the SEC on February 28, 2023. 10.39 Third Amendment to Commercial Lease, executed April 14, 2025, by and between the Registrant and Tannos Land Holdings III, LLC incorporated by reference to Exhibit 10.2 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on May 5, 2025 . 10.40† Lease Agreement, dated April 1, 2022, by and between the Registrant and ACA Concourse East Unit 3 LLC, incorporated by reference to Exhibit 10.3 of the Registrant ’ s Quarterly Report on Form 10-Q filed with the SEC on May 9, 2022. 10.41#† First Amendment to Lease Agreement, dated March 26, 2024 by and between the Registrant and ACA Concourse East Unit 3 LLC, incorporated by reference to Exhibit 10.2 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on May 2, 2024. 10.42 Confirmation of Amendment Provisions, dated as of August 8, 2024, to the Lease Agreement, dated April 1, 2022, by and between the Registrant and ACA Concourse East Unit 3 LLC, incorporated by reference to Exhibit 10.1 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on November 4, 2024. 10.43 Office Lease Agreement dated May 14, 2025, by and between the Registrant and Perimeter Gateway Portfolio LLC , incorporated by reference to Exhibit 10.3 of the Registrant ’ s Quarterly Report on Form 10-Q filed with the SEC on Augu st 4, 2025. Purchase Sale Agreements 10.44 Purchase Sale Agreement of Land, dated Jul 10, 2023, by and between the Registrant and Hal B. Boone, incorporated by reference to Exhibit 10.1 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on November 2, 2023. 10.45 First Amendment to Purchase Sale Agreement of Land, dated October 4, 2023, by and between the Registrant and Hal B. Boone, incorporated by reference to Exhibit 10.3 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on November 2, 2023. 109 Table of Contents Exhibit Number Description of document 10.46† Second Amendment to Purchase Sale Agreement of Land, dated January 9, 2024, by and between the Registrant and Hal B. Boone, incorporated by reference to Exhibit 10.38 of the Registrant ’ s Annual Report on Form 10-K filed with the SEC on February 28, 2024. Loan and Security Agreements 10.47# Loan and Security Agreement, dated March 26, 2024, by and among the Registrant and Silicon Valley Bank, incorporated by reference to Exhibit 10.1 of the Registrant’s Current Report on Form 8-K filed with the SEC on March 27, 2024. 10.48#† Consent and First Amendment to the Loan and Security Agreement, dated April 4, 2025, by and among the Registrant, Castle Narnia Way Real Estate Holding 1, LLC and Silicon Valley Bank incorporated by reference to Exhibit 10.1 of the Registrant’s Quarterly Report on Form 10-Q filed with the SEC on May 5, 2025 Other Agreements 10.49# Exclusive License Agreement, dated as of November 14, 2009, by and between the Registrant and The Washington University, incorporated by reference to Exhibit 10.17 of the Registrant’s Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on June 26, 2019. Other Exhibits 19.1 Insider Trading Policy, incorporated by reference to Exhibit 19.1 of the Registrant ’ s Annual Report on Form 10-K filed with the SEC on February 27, 2025. 21.1* Subsidiaries of the Registrant. 23.1* Consent of KPMG LLP, Independent Registered Public Accounting Firm. 24.1* P ower of Attorney. Reference is made to the signature page hereto. 31.1* Certification of Principal Executive Officer pursuant to Rules 13a-14(a) and 15d-14(a) of the Exchange Act. 31.2* Certification of Principal Financial Officer pursuant to Rules 13a-14(a) and 15d-14(a) of the Exchange Act. 32.1** Certification of Principal Executive Officer and Principal Financial Officer pursuant to Rules 13a-14(b) or 15d-14(b) of the Exchange Act, and 18 U.S.C. Section 1350. 97.1+ Castle Biosciences, Inc. Incentive Compensation Recoupment Policy, incorporated by reference to Exhibit 97.1 of the Registrant's Annual Report on Form 10-K filed with the SEC on February 28, 2024. 101.INS* Inline XBRL Instance Document—the instance document does not appear in the Interactive Data File as its XBRL tags are embedded within the Inline XBRL document. 101.SCH* Inline XBRL Taxonomy Extension Schema. 101.CAL* Inline XBRL Taxonomy Extension Calculation Linkbase. 101.DEF* Inline XBRL Taxonomy Extension Definition Linkbase. 101.LAB* Inline XBRL Taxonomy Extension Label Linkbase. 101.PRE* Inline XBRL Taxonomy Extension Presentation Linkbase. 104* Cover Page Interactive Data File (embedded within the Inline XBRL and contained in Exhibit 101). * Filed herewith ** Furnished herewith. + Indicates management contract or compensatory plan. # Pursuant to Item 601(b)(10) of Regulation S-K, certain portions of this exhibit have been omitted (indicated by “[***]”) because the Company has determined that the information is not material and is the type that the Company treats as private or confidential. † Certain schedules or exhibits have been omitted pursuant to Item 601(a)(5) of Regulation S-K. A copy of any omitted schedule or exhibit will be furnished to the SEC upon request; provided, however, that we may request confidential treatment pursuant to Rule 24b-2 of the Exchange Act for any schedule or exhibit so furnished. ^ Pursuant to Item 601(b)(2) of Regulation S-K, certain portions of this exhibit have been omitted (indicated by “[***]”) because the Company has determined that the information is not material and is the type that the Company treats as private or confidential. Item 16. Form 10-K Summary. None. 110 Table of Contents SIGNATURES Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized. CASTLE BIOSCIENCES, INC. Date: February 26, 2026 By: /s/ Derek J. Maetzold Derek J. Maetzold President and Chief Executive Officer (Principal Executive Officer) KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Derek J. Maetzold and Frank Stokes and each of them, as his or her true and lawful attorneys-in-fact and agents, each with the full power of substitution, for him or her and in his or her name, place or stead, in any and all capacities, to sign any and all amendments to this Annual Report on Form 10‑K, and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or their or his substitute or substitutes, may lawfully do or cause to be done by virtue hereof. 111 Table of Contents Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the Registrant and in the capacity and on the dates indicated. SIGNATURE TITLE DATE /s/ Derek J. Maetzold President, Chief Executive Officer and Director February 26, 2026 (Derek J. Maetzold) ( Principal Executive Officer ) /s/ Frank Stokes Chief Financial Officer February 26, 2026 (Frank Stokes) ( Principal Financial and Accounting Officer ) /s/ Daniel M. Bradbury Chairperson of the Board of Directors February 26, 2026 (Daniel M. Bradbury) /s/ Kimberlee S. Caple Member of the Board of Directors February 26, 2026 (Kimberlee S. Caple) /s/ G. Bradley Cole Member of the Board of Directors February 26, 2026 (G. Bradley Cole) /s/ Rodney Cotton Member of the Board of Directors February 26, 2026 (Rodney Cotton) /s/ Ellen Goldberg Member of the Board of Directors February 26, 2026 (Ellen Goldberg) /s/ Miles D. Harrison Member of the Board of Directors February 26, 2026 (Miles D. Harrison) /s/ Tiffany P. Olson Member of the Board of Directors February 26, 2026 (Tiffany P. Olson) 112 Table of Contents INDEX TO CONSOLIDATED FINANCIAL STATEMENTS Page Report of Independent Registered Public Accounting Firm ( PCA OB ID: 185) F- 2 Consolidated Balance Sheets as of December 31, 2025 and 2024 F- 4 Consolidated Statements of Operations for the Years Ended December 31, 2025, 2024 and 2023 F- 5 Consolidated Statements of Comprehensive (Loss) Income for the Years Ended December 31, 2025, 2024 and 2023 F- 6 Consolidated Statements of Stockholders’ Equity for the Years Ended December 31, 2025, 2024 and 2023 F- 7 Consolidated Statements of Cash Flows for the Years Ended December 31, 2025, 2024 and 2023 F- 8 Notes to the Consolidated Financial Statements F-10 F-1 Table of Contents Report of Independent Registered Public Accounting Firm To the Stockholders and Board of Directors Castle Biosciences, Inc.: Opinions on the Consolidated Financial Statements and Internal Control Over Financial Reporting We have audited the accompanying consolidated balance sheets of Castle Biosciences, Inc. and subsidiaries (the Company) as of December 31, 2025 and 2024, the related consolidated statements of operations, comprehensive (loss) income, stockholders’ equity, and cash flows for each of the years in the three-year period ended December 31, 2025, and the related notes (collectively, the consolidated financial statements). We also have audited the Company’s internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control – Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the years in the three-year period ended December 31, 2025, in conformity with U.S. generally accepted accounting principles. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2025 based on criteria established in Internal Control – Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. Basis for Opinions The Company’s management is responsible for these consolidated financial statements, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying Management’s Report on Internal Control over Financial Reporting. Our responsibility is to express an opinion on the Company’s consolidated financial statements and an opinion on the Company’s internal control over financial reporting based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB. We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud, and whether effective internal control over financial reporting was maintained in all material respects. Our audits of the consolidated financial statements included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions. Definition and Limitations of Internal Control Over Financial Reporting A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements. F-2 Table of Contents Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate. Critical Audit Matter The critical audit matter communicated below is a matter arising from the current period audit of the consolidated financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the consolidated financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of a critical audit matter does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates. Measurement of test revenue As discussed in Notes 2 and 3 of the consolidated financial statements, test revenue is recognized when the performance obligation is satisfied, upon delivery of the test report. The amount of revenue recognized reflects the amount of consideration to which the Company expects to be entitled and considers the effects of variable consideration. The measurement of test revenue is determined by contractually established rates as well as historical average collection rates by test type and payor category taking into consideration the range of possible outcomes, the predictive value of the Company’s past experiences, the time period of when uncertainties expect to be resolved and the amount of consideration that is susceptible to factors outside of the Company’s influence, such as the judgment and actions of third parties. The Company reported net revenues of $344.2 million for the year ended December 31, 2025, a portion of which related to test revenue. We identified the evaluation of the measurement of test revenue as a critical audit matter. Evaluating the measurement of test revenue, specifically the estimation of the amount of test revenue expected to be collectible related to commercial payors and certain others, required especially complex and subjective auditor judgment. The following are the primary procedures we performed to address this critical audit matter. We evaluated the design and tested the operating effectiveness of certain internal controls related to the estimation of the expected collectible test revenue related to commercial payors and certain others. This included controls related to management’s review of the assumptions and inputs used in the determination of test revenue expected to be collectible from commercial payors and certain others. For a selection of tests, we evaluated certain historical data inputs that are used in management’s model to estimate test revenue expected to be collectible by comparing the data from the model to physician test requisition forms, proof of delivery, and cash collection activity. These data inputs included collection activity, amounts of historical claims, insurance payor categories, test dates, test types, claim aging categories, and revenue recognition dates. In addition, we inquired of the individuals who are responsible for monitoring and tracking the status of anticipated collections to understand the progress of these activities and any impact to management’s estimates. /s/ KPMG LLP We have served as the Company’s auditor since 2018. Houston, Texas February 26, 2026 F-3 Table of Contents CASTLE BIOSCIENCES, INC. CONSOLIDATED BALANCE SHEETS (in thousands, except share and per share data) December 31, 2025 2024 ASSETS Current Assets Cash and cash equivalents $ 116,729 $ 119,709 Marketable investment securities 182,776 173,421 Accounts receivable, net 43,382 51,218 Inventory 10,254 8,135 Prepaid expenses and other current assets 7,956 7,671 Total current assets 361,097 360,154 Long-term accounts receivable, net 1,878 918 Property and equipment, net 97,443 51,122 Operating lease assets 14,795 11,584 Goodwill and other intangible assets, net 99,574 106,229 Other assets – long-term 3,769 1,228 Total assets $ 578,556 $ 531,235 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Accounts payable $ 18,711 $ 6,901 Accrued compensation 38,287 32,555 Contingent consideration 1,000 — Operating lease liabilities 1,325 1,665 Current portion of long-term debt 417 278 Other accrued and current liabilities 8,937 7,993 Total current liabilities 68,677 49,392 Long-term debt 9,640 9,745 Noncurrent portion of contingent consideration 1,500 — Noncurrent operating lease liabilities 25,217 14,345 Noncurrent finance lease liabilities 314 311 Deferred tax liability 2,335 1,607 Total liabilities 107,683 75,400 Commitments and Contingencies (Note 12) Stockholders’ Equity Preferred stock, $ 0.001 par value per share; 10,000,000 shares authorized as of December 31, 2025 and 2024; no shares issued and outstanding as of December 31, 2025 and 2024 — — Common stock, $ 0.001 par value per share; 200,000,000 authorized as of December 31, 2025 and 2024; 29,686,314 and 28,483,195 shares issued and outstanding as of December 31, 2025 and 2024, respectively 30 28 Additional paid-in capital 694,860 655,703 Accumulated deficit ( 224,284 ) ( 200,126 ) Accumulated other comprehensive income 267 230 Total stockholders’ equity 470,873 455,835 Total liabilities and stockholders’ equity $ 578,556 $ 531,235 The accompanying notes are an integral part of these consolidated financial statements. F-4 Table of Contents CASTLE BIOSCIENCES, INC. CONSOLIDATED STATEMENTS OF OPERATIONS (in thousands, except per share data) Years Ended December 31, 2025 2024 2023 NET REVENUES $ 344,229 $ 332,069 $ 219,788 OPERATING EXPENSES Cost of sales (exclusive of amortization of acquired intangible assets) 71,028 60,205 44,982 Research and development 51,850 52,041 53,618 Selling, general and administrative 229,323 200,047 180,152 Amortization of acquired intangible assets 34,838 11,106 9,013 Total operating expenses, net 387,039 323,399 287,765 Operating (loss) income ( 42,810 ) 8,670 ( 67,977 ) Interest income 11,772 12,916 10,623 Net gains on equity securities 1,466 555 — Interest expense ( 86 ) ( 577 ) ( 11 ) Other income 144 — — (Loss) income before income taxes ( 29,514 ) 21,564 ( 57,365 ) Income tax (benefit) expense ( 5,356 ) 3,319 101 Net (loss) income $ ( 24,158 ) $ 18,245 $ ( 57,466 ) (Loss) earnings per share: Basic $ ( 0.83 ) $ 0.66 $ ( 2.14 ) Diluted $ ( 0.83 ) $ 0.62 $ ( 2.14 ) Weighted-average shares outstanding: Basic 28,986 27,776 26,802 Diluted 28,986 29,255 26,802 The accompanying notes are an integral part of these consolidated financial statements. F-5 Table of Contents CASTLE BIOSCIENCES, INC. CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME (in thousands) Years Ended December 31, 2025 2024 2023 Net (loss) income $ ( 24,158 ) $ 18,245 $ ( 57,466 ) Other comprehensive income: Net unrealized gain on marketable investment securities 37 94 517 Comprehensive (loss) income $ ( 24,121 ) $ 18,339 $ ( 56,949 ) The accompanying notes are an integral part of these consolidated financial statements. F-6 Table of Contents CASTLE BIOSCIENCES, INC. CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (in thousands, except share data) Common Stock Additional Paid-in Capital Accumulated Deficit Accumulated Other Comprehensive (Loss) Income Total Stockholders’ Equity Shares Amount BALANCE, JANUARY 1, 2023 26,553,681 $ 27 $ 560,409 $ ( 160,905 ) $ ( 381 ) $ 399,150 Stock-based compensation expense — — 51,219 — — 51,219 Exercise of common stock options 71,525 — 269 — — 269 Issuance of common stock from vested restricted stock units, net of shares withheld for taxes 645,454 — ( 5,134 ) — — ( 5,134 ) Issuance of common stock under the employee stock purchase plan 139,872 — 2,714 — — 2,714 Net unrealized gain on marketable investment securities — — — — 517 517 Net loss — — — ( 57,466 ) — ( 57,466 ) BALANCE, DECEMBER 31, 2023 27,410,532 $ 27 $ 609,477 $ ( 218,371 ) $ 136 $ 391,269 Stock-based compensation expense — — 50,320 — — 50,320 Exercise of common stock options 135,875 — 2,017 — — 2,017 Issuance of common stock from vested restricted stock units, performance stock units, net of shares withheld for taxes 769,100 — ( 8,762 ) — — ( 8,762 ) Issuance of common stock under the employee stock purchase plan 167,688 1 2,651 — — 2,652 Net unrealized gain on marketable investment securities — — — — 94 94 Net income — — — 18,245 — 18,245 BALANCE, DECEMBER 31, 2024 28,483,195 $ 28 $ 655,703 $ ( 200,126 ) $ 230 $ 455,835 Stock-based compensation expense — — 45,893 — — 45,893 Exercise of common stock options 108,458 — 2,206 — — 2,206 Issuance of common stock from vested restricted stock units, net of shares withheld for taxes 933,763 1 ( 11,658 ) — — ( 11,657 ) Issuance of common stock under the employee stock purchase plan 160,898 1 2,716 — — 2,717 Net unrealized gain on marketable investment securities — — — — 37 37 Net loss — — — ( 24,158 ) — ( 24,158 ) BALANCE, DECEMBER 31, 2025 29,686,314 $ 30 $ 694,860 $ ( 224,284 ) $ 267 $ 470,873 The accompanying notes are an integral part of these consolidated financial statements. F-7 Table of Contents CASTLE BIOSCIENCES, INC. CONSOLIDATED STATEMENTS OF CASH FLOWS (in thousands) Years Ended December 31, 2025 2024 2023 OPERATING ACTIVITIES Net (loss) income $ ( 24,158 ) $ 18,245 $ ( 57,466 ) Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities: Depreciation and amortization 40,771 15,997 12,330 Stock-based compensation expense 45,893 50,320 51,219 Net gains on equity securities ( 1,466 ) ( 555 ) — Deferred income taxes ( 6,228 ) 1,401 ( 223 ) Accretion of discounts on marketable investment securities ( 4,219 ) ( 6,685 ) ( 5,491 ) Other 153 268 635 Change in operating assets and liabilities: Accounts receivable 6,876 ( 12,643 ) ( 14,930 ) Prepaid expenses and other current assets ( 544 ) ( 1,142 ) ( 435 ) Inventory ( 2,142 ) ( 193 ) ( 3,962 ) Operating lease assets 1,372 1,322 ( 258 ) Other assets ( 366 ) 262 ( 330 ) Accounts payable 3,078 ( 4,372 ) 5,707 Operating lease liabilities ( 1,275 ) ( 1,289 ) 852 Accrued compensation 5,732 3,610 4,587 Other accrued and current liabilities 870 320 2,139 Net cash provided by (used in) operating activities 64,347 64,866 ( 5,626 ) INVESTING ACTIVITIES Purchases of marketable investment securities ( 188,714 ) ( 205,729 ) ( 189,075 ) Proceeds from maturities of marketable investment securities 189,200 183,900 186,500 Proceeds from sale of equity securities 1,533 — — Purchases of debt securities classified as held-to-maturity ( 5,569 ) — — Asset acquisition, net of cash and cash equivalents acquired ( 18,727 ) — — Issuance of loan receivable ( 2,114 ) — — Purchases of property and equipment ( 36,021 ) ( 28,326 ) ( 13,621 ) Proceeds from sale of property and equipment 45 18 13 Net cash used in investing activities ( 60,367 ) ( 50,137 ) ( 16,183 ) FINANCING ACTIVITIES Proceeds from exercise of common stock options 2,206 2,017 269 Payment of employees’ taxes on vested restricted stock units ( 11,657 ) ( 8,762 ) ( 5,134 ) Proceeds from contributions to the employee stock purchase plan 2,416 2,981 2,709 Repayment of principal portion of finance lease liabilities ( 115 ) ( 97 ) ( 142 ) Proceeds from lease incentives received 190 — — Proceeds from issuance of term debt — 10,000 — Net cash (used in) provided by financing activities ( 6,960 ) 6,139 ( 2,298 ) NET CHANGE IN CASH AND CASH EQUIVALENTS ( 2,980 ) 20,868 ( 24,107 ) Beginning of year 119,709 98,841 122,948 End of year $ 116,729 $ 119,709 $ 98,841 The accompanying notes are an integral part of these consolidated financial statements. F-8 Table of Contents CASTLE BIOSCIENCES, INC. CONSOLIDATED STATEMENTS OF CASH FLOWS (Continued) (in thousands) Years Ended December 31, 2025 2024 2023 SUPPLEMENTAL DISCLOSURE OF CASH PAID FOR: Interest paid, net of amounts capitalized $ 59 $ 434 $ 11 Income taxes, net $ 1,601 $ 2,503 $ 198 DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES: Asset acquisition, liability for contingent consideration $ 2,500 $ — $ — Accrued purchases of property and equipment $ 11,337 $ 2,231 $ 1,226 Property and equipment acquired with tenant improvement allowance $ 7,224 $ 1,389 $ 1,281 Operating lease assets obtained in exchange for lease obligations $ 4,687 $ 607 $ 1,547 Decrease in operating lease assets with corresponding change in lease liabilities $ ( 104 ) $ ( 7 ) $ — Finance lease assets obtained in exchange for lease obligations $ 119 $ 218 $ — The accompanying notes are an integral part of these consolidated financial statements. F-9 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS 1. Organization and Description of Business Castle Biosciences, Inc. (the “Company,” “we,” “us” or “our”) was incorporated in the state of Delaware on September 12, 2007. We are a commercial-stage diagnostics company focused on providing clinicians and their patients with personalized, clinically actionable information to inform treatment decisions and improve health outcomes. We are based in Friendswood, Texas (a suburb of Houston, Texas) and our laboratory operations are conducted at our facilities located in Phoenix, Arizona and Pittsburgh, Pennsylvania. 2. Summary of Significant Accounting Policies Basis of Presentation The consolidated financial statements include the accounts of Castle Biosciences, Inc. and our wholly owned subsidiaries and have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). All intercompany accounts and transactions have been eliminated in consolidation. In connection with preparing consolidated financial statements for each annual and interim reporting period, the Company is required to evaluate whether there are conditions or events, considered in aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. Substantial doubt exists when conditions and events, considered in aggregate, indicate that it is probable that a company will be unable to meet its obligations as they become due within one year after the date that the consolidated financial statements are issued. This evaluation initially does not take into consideration the potential mitigating effect of management’s plans and actions that have not been fully implemented as of the date that the financial statements are issued. When substantial doubt exists, management evaluates whether the mitigating effect of its plans sufficiently alleviates substantial doubt about the Company’s ability to continue as a going concern. The mitigating effect of management’s plans, however, is only considered if both: (1) it is probable that the plans will be effectively implemented within one year after the date that the financial statements are issued; and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. Generally, to be considered probable of being effectively implemented, the plans must have been approved before the date that the financial statements are issued. We have a history of recurring net losses and negative cash flows and as of December 31, 2025, we had an accumulated deficit of $ 224.3 million. We believe our $ 116.7 million of cash and cash equivalents and $ 182.8 million of marketable investment securities as of December 31, 2025, and anticipated revenue from our test reports will be sufficient to meet our cash requirements through at least the 12-month period following the date that these consolidated financial statements were issued. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Significant items subject to such estimates include revenue recognition, the valuation of stock-based compensation, assessing future tax exposure and the realizability of deferred tax assets, the useful lives and recoverability of long-lived assets, the goodwill impairment test, the valuation of acquired intangible assets, allowance for credit losses for assets measured at amortized cost, the valuation of contingent consideration, and other contingent liabilities. We base these estimates on historical and anticipated results, trends and various other assumptions that we believe are reasonable under the circumstances, including assumptions as to future events. These estimates form the basis for making judgments about the carrying values of assets and liabilities and recorded revenues and expenses that are not readily apparent from other sources. Actual results could differ from those estimates and assumptions. F-10 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Segment Reporting Operating segments are components of an enterprise engaging in business activities from which it may recognize revenues and incur expenses, where discrete financial information is available, and where its operating results are regularly reviewed by the public entity’s chief operating decision maker (“CODM”) to make decisions about resources to be allocated to the segment and to assess its performance. A CODM may be an individual or a decision-making group. A reportable segment consists of one or more operating segments. For additional information on our segment reporting, see Note 16. Cash and Cash Equivalents including Concentrations of Credit Risk Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less. Our cash equivalents consist of money market funds, which are not insured by the Federal Deposit Insurance Corporation (“FDIC”), that are primarily invested in short-term U.S. government obligations. Cash deposits at financial institutions may exceed the amount of insurance provided by the FDIC. Management believes that we are not exposed to significant credit risk on our cash deposits due to the financial position of the financial institutions in which deposits are held. Marketable Investment Securities Our marketable investment securities are comprised of debt and equity securities. All debt securities are recognized in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 320, Investments-Debt Securities (“ASC 320”). Management determines the appropriate classification of debt securities at the time of purchase and re-evaluates such determination at each balance sheet date. Debt securities that are classified as available-for-sale (“AFS”) are recorded at fair value in accordance with ASC 320. We recognize the unrealized gains and losses related to changes in fair value as a separate component of accumulated other comprehensive (loss) income within total stockholders’ equity, net of any related deferred income tax effects, on the consolidated balance sheets. Debt securities that are classified as held-to-maturity (“HTM”) are reported at amortized cost in accordance with ASC 320. Premiums or discounts from par value are amortized to interest income over the life of the underlying investment and are included in interest income in the consolidated statements of operations. Realized gains and losses on AFS and HTM debt securities, if any, are calculated at the individual security level and are included in interest income in the consolidated statements of operations. Impairments of AFS or HTM debt securities, if any, are recorded in the consolidated statements of operations. Our equity securities consist of investments in shares of common stock which are listed and traded on the Nasdaq Global Market and certain foreign exchanges. All equity securities are recognized in accordance with ASC Topic 321, Investments-Equity Securities (“ASC 321”) and reported at their readily determinable fair values based on quoted market prices where changes in fair value are included in net gains on equity securities in the consolidated statements of operations. For investments denominated in a foreign currency, the fair value is remeasured into U.S. dollars using exchange rates in effect at each balance sheet date in accordance with ASC Topic 830, Foreign Currency Matters (“ASC 830”). As a result, changes in fair value include the effects of both market price movements and foreign currency exchange rate fluctuations. All changes in a marketable security’s fair value are reported in earnings as they occur, and the sale of our equity securities does not necessarily give rise to a significant gain or loss. Investments in equity securities are classified as either current or long-term depending upon management’s intentions. We updated our terminology to refer to these investments as equity securities rather than trading securities to align with the terminology in ASC 321. See Notes 5 and 11 for further details. Revenue Recognition In accordance with ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”), we follow a five-step process to recognize revenues: (1) identify the contract with the customer, (2) identify the performance obligations, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations and (5) recognize revenues when the performance obligations are satisfied. We have determined that we have a contract with the patient when the treating clinician orders the test. Our contracts generally contain a single performance obligation, which is the delivery of the test report, and we satisfy our performance obligation at a point in time upon the delivery of the test report to the treating clinician, at which point we can bill for the report. The amount of revenue recognized reflects the amount of consideration to which we expect to be entitled, or the transaction price, and considers the effects of variable consideration. See Note 3 for further details. F-11 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Collaborative Arrangements We assess whether our licensing and other agreements are collaborative arrangements based on whether they involve joint operating activities and whether both parties have active participation in the arrangement and are exposed to significant risks and rewards. For arrangements that we determine are collaborations, we identify each unit of account and then determine whether a customer relationship exists for that unit of account. If we determine that a performance obligation within the collaborative arrangement is with a customer, we apply ASC 606. If a portion of a distinct bundle of goods or services within the collaborative arrangement is not with a customer, we apply recognition and measurement based on an analogy to authoritative accounting literature or, if there is no appropriate analogy, a reasonable, rational, and consistently applied accounting policy election. To the extent the arrangement is within the scope of ASC Topic 808, Collaborative Arrangements (“ASC 808”), we assess whether aspects of the arrangement are within the scope of other accounting literature. In June 2025, we entered into a Collaboration and License Agreement with SciBase Holding AB (“SciBase”). Following approval under the Swedish Screening of Foreign Direct Investments Act in the third quarter of 2025, subsequent to approval, we completed our investment in SciBase. The agreement aims to jointly develop diagnostic tests for dermatologic diseases, initially focused on atopic dermatitis, by combining SciBase’s Electrical Impedance Spectroscopy technology with our diagnostic and development expertise. Under the arrangement, we hold development and commercialization rights in North America, while SciBase retains rights in certain other territories. SciBase is entitled to royalties on our product sales, a mark-up on product sales to us, and a milestone payment upon achieving specified sales thresholds. Development costs are shared; however, SciBase deferred its initial clinical development costs for the initial indication and we will recover those costs through future royalty payments reductions. We determined the agreement is a collaborative arrangement under ASC 808. Certain elements of the arrangement, including license rights and sales-based royalty provisions, represent transactions with a customer and are therefore accounted for under ASC 606. Other elements, such as shared development activities and cost reimbursements, are accounted for in accordance with ASC 808 and presented as reductions to research and development (“R&D”) expenses. Accounts Receivable and Allowance for Credit Losses We classify accounts receivable balances that are expected to be paid more than one year from the consolidated balance sheet date as noncurrent assets. The estimated timing of payment utilized as a basis for classification as noncurrent is determined by analyses of historical payor-specific payment experience, adjusted for known factors that are expected to change the timing of future payments. We accrue an allowance for credit losses against our accounts receivable based on management’s current estimate of amounts that will not be collected. Management’s estimates are typically based on historical loss information adjusted for current conditions. We generally do not perform evaluations of customers’ financial condition and generally do not require collateral. Historically, our credit losses have not been significant. The allowance for credit losses was zero as of December 31, 2025 and 2024. Adjustments for implicit price concessions attributable to variable consideration, as discussed below, are incorporated into the measurement of the accounts receivable balances and are not part of the allowance for credit losses. F-12 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Convertible Loan Receivable On November 7, 2025, we entered into a Convertible Loan Agreement with SciBase (the “Convertible Loan Receivable”), pursuant to which we loaned SEK 20.0 million, approximately $ 2.1 million based on the exchange rate in effect on November 7, 2025. The Convertible Loan Receivable bears interest at a rate of 2.00 % plus the three-month Stockholm Interbank Offered Rate (“STIBOR”), payable quarterly. SciBase may prepay all or a portion of the Convertible Loan Receivable at any time. The Convertible Loan Receivable matures on November 7, 2030, at which time we have the option, at our sole discretion, to convert the outstanding principal plus accrued interest into shares of SciBase that are listed on the Nasdaq First North Growth Market in Sweden, receive full repayment in cash, or receive a combination of cash and shares. We accounted for the convertible loan as a receivable within the scope of ASC Topic 310, Receivables. The carrying amount of the convertible loan is presented at amortized cost, within long-term other assets in the consolidated balance sheets. The Convertible Loan Agreement is remeasured into U.S. dollars using exchange rates in effect at each balance sheet date in accordance with ASC 830 with changes in exchange rates recognized in earnings. In addition, the embedded conversion feature to shares of SciBase did not meet the definition of a derivative and was not bifurcated from the host contract under ASC Topic 815, Derivatives and Hedging . We have determined that expected credit losses associated with the loan are insignificant and, accordingly, have not recorded a credit loss allowance under ASC Topic 326-20, Financial Instruments - Credit Losses. Interest income on the Convertible Loan Receivable is recognized quarterly and included in interest income in the consolidated statements of operations. Accrued interest receivable is recorded within prepaid expenses and other current assets in the consolidated balance sheets. Inventory We carry inventories of test supplies in our laboratory facilities. The inventories are carried at the lower of weighted average cost and net realizable value and expensed through cost of sales as the supplies are used. Property and Equipment Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, generally between five and ten years . Leasehold improvements are amortized using the straight-line method over the shorter of the estimated useful life of the asset or the term of the lease. Our leasehold improvements primarily relate to our office and laboratory facilities located in Friendswood, Texas, Phoenix, Arizona and Pittsburgh, Pennsylvania, and are generally depreciated over the remaining lease terms, which end in 2026, 2034 and 2033, respectively. Maintenance and repairs are charged to expense as incurred, and material improvements are capitalized. Interest costs incurred during the construction of major capital projects are capitalized until the underlying asset is ready for its intended use, at which point the capitalized interest costs are amortized using the straight-line method over the estimated useful life of the underlying asset. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the consolidated balance sheet and any resulting gain or loss is reflected in the consolidated statements of operations in the period realized. Intangible Assets Our intangible assets, which are comprised primarily of acquired developed technology, are considered to be finite-lived and are amortized on a straight-line basis over their estimated useful lives. Goodwill Goodwill represents the excess of the purchase price over the fair value of the net tangible and intangible assets acquired in a business combination. Goodwill is not amortized, but is tested for impairment. We test goodwill for impairment in the fourth quarter of each fiscal year and when events, or changes in circumstances, indicate that it may be impaired. Events and changes in circumstances indicating that goodwill may be impaired include sustained declines in the price of our common stock, increased competition, changes in macroeconomic developments, unfavorable government or regulatory developments and changes in coverage or reimbursement conditions. F-13 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Goodwill is tested for impairment at the reporting unit level where goodwill is held. Testing begins with completion of an optional qualitative assessment. If the qualitative assessment suggests that impairment is more likely than not, quantitative testing is conducted. If the qualitative assessment is bypassed, we proceed directly to quantitative testing. Quantitative testing consists of comparing the carrying value of goodwill to its estimated fair value. Impairment of goodwill is the condition that exists when the carrying value exceeds its fair value. Amounts by which carrying value exceed fair value, up to the total amount of goodwill allocated to the reporting unit, are recognized as an impairment loss in the consolidated statements of operations. Long-Lived Assets We review long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. An impairment loss is recognized when the total of estimated future undiscounted cash flows, expected to result from the use of the asset and its eventual disposition, are less than the carrying amount. Impairment, if any, would be calculated based on the excess of the carrying amount of the long-lived asset over the long-lived asset’s fair value. There were no impairment charges recognized during the years ended December 31, 2025, 2024 and 2023. Acquisitions We assess acquisitions under ASC Topic 805, Business Combinations (“ASC 805”) , to determine whether a transaction represents the acquisition of assets or a business combination. Under this guidance, we apply a two-step model. The first step involves a screening test where we evaluate whether substantially all of the fair value of the gross assets acquired is concentrated in a single asset or a group of similar assets. If the screening test is met, we account for the set as an asset acquisition. If the screening test is not met, we apply the second step of the model to determine if the set meets the definition of a business based on the guidance in ASC 805. If so, the transaction is treated as a business combination. Otherwise, it is treated as an asset acquisition. Asset acquisitions are accounted for by allocating the cost of the acquisition, including transaction costs, to the individual assets acquired and liabilities assumed on a relative fair value basis without recognition of goodwill. If the total consideration transferred is less than the aggregate fair value of the net assets acquired (i.e., a bargain purchase), the difference is not recognized as a gain. Instead, the difference is allocated to the cost of the acquired assets on a relative fair value basis. Business combinations are accounted for using the acquisition method. Under the acquisition method, goodwill is measured as a residual amount equal to the fair value of the consideration transferred less the net recognized fair value of the identifiable assets acquired and the liabilities assumed, as of the acquisition date, and transaction costs are expensed as incurred. Contingent Consideration Under the terms of business combinations or asset acquisitions, we may be required to pay additional consideration if specified future events occur or if certain conditions are met. In May 2025, we acquired Capsulomics, Inc., d/b/a Previse (“Previse”), which was recorded as an asset acquisition, and agreed to pay additional consideration of up to $ 2.5 million in cash based on the achievement of certain commercial milestones (the “Earnout Payments”). We account for the contingent consideration as a liability in accordance with ASC Topic 450-20, Loss Contingencies (“ASC 450-20”) when it is both probable and reasonably estimable. In accordance with ASC 450-20, we recorded the contingent consideration at the amount required to settle the respective obligation, and subsequent changes are recognized as adjustments to the cost basis of the acquired assets. These changes are allocated to the acquired assets based on their relative fair values as of the date of acquisition. In December of 2025, one of the commercial milestones was achieved. As a result, an Earnout Payment of $ 0.5 million became payable and will be paid within 60 days of milestone achievement. Contingent consideration is classified as current or noncurrent in the consolidated balance sheets based on the contractual timing of future settlement. F-14 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Leases We account for leases in accordance with ASC Topic 842, Leases (“ ASC 842”) . We categorize leases at their commencement as either operating or finance leases based on the criteria in ASC 842. Under ASC 842, we record right-of-use (“ROU”) assets and lease liabilities for each lease arrangement identified, except that we have elected the short-term lease exemption for all leases with a term of 12 months or less. Lease liabilities are recorded at the present value of future lease payments discounted using our incremental borrowing rate for the lease established at the commencement date and ROU assets are measured at the amount of the lease liability plus any initial direct costs, less any lease incentives received before commencement. For our operating leases, we recognize a single lease cost over the lease term on a straight-line basis. We have elected the practical expedient of not separating nonlease components from lease components in all leases. See Note 10 for details on our leases. Cost of Sales (exclusive of amortization of acquired intangible assets) Cost of sales is expensed as incurred and includes material and service costs associated with testing samples, personnel costs (including salaries, bonuses, benefits and stock-based compensation expense), electronic medical records, order and delivery systems, shipping charges to transport samples, third-party test fees, and allocated overhead including rent, information technology costs, equipment and facilities depreciation and utilities. Research and Development R&D costs are charged to operations as incurred. Advance payments for goods and services that will be used in future R&D activities are expensed when the activity has been performed or when the goods have been received rather than when the payment is made. Upfront and milestone payments due to third parties that perform R&D services on behalf of us will be expensed as services are rendered or when the milestone is achieved. R&D costs include, but are not limited to, payroll and personnel-related expenses, stock-based compensation expense, materials, laboratory supplies and consulting costs. Selling, General and Administrative Expenses Selling, general and administrative (“SG&A”) expenses are attributable to sales, marketing, executive, finance and accounting, legal and human resources functions. These expenses consist of personnel costs (including salaries, employee benefit costs, bonuses and stock-based compensation expenses), customer services expenses, direct marketing expenses, educational and promotional expenses, market research, audit and legal expenses and consulting. We expense all SG&A costs as incurred. Accrued Compensation We accrue for liabilities under discretionary employee and executive bonus plans. Our estimated compensation liabilities are based on progress against corporate objectives approved by our board of directors, compensation levels of eligible individuals and target bonus percentage levels. Our board of directors reviews and evaluates the performance against these objectives and ultimately determines the actual achievement levels attained. We also accrue for liabilities under employee sales incentive bonus plans with accruals based on performance achieved to date compared to established targets. As of December 31, 2025 and 2024, we accrued approximately $ 28.1 million and $ 23.3 million, respectively, for liabilities associated with these bonus plans. These amounts are classified as current or noncurrent accrued liabilities based on the expected timing of payment. Retirement Plan We have an Internal Revenue Code (“IRC”) Section 401(k) profit sharing plan (the “Plan”) for eligible employees. The Plan is funded by employee contributions and provides for discretionary contributions in the form of matching and/or profit-sharing contributions. For the years ended December 31, 2025, 2024 and 2023 we provided a discretionary matching contribution of $ 6.1 million, $ 5.5 million and $ 4.6 million respectively. The higher amount for the year ended December 31, 2025 primarily reflects an increase in the number of employees compared to the years ended December 31, 2024 and 2023. F-15 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Income Taxes We use the asset and liability method of accounting for income taxes. Current income taxes are recognized for the estimated taxes payable or refundable on tax returns for the current year. Deferred income taxes arise from the recognition of temporary differences between financial statement carrying amounts and the tax basis of assets and liabilities. We consider all evidence, both positive and negative, with respect to our net operating loss (“NOL”) carryforwards, expected levels of pre-tax financial statement income (loss), taxable income (benefit), liquidity, and prudent and reasonable tax planning strategies when evaluating whether the temporary differences will be realized. In projecting future taxable income (loss), we begin with budgeted pre-tax income (loss) adjusted for estimated taxable and non-taxable items. The assumptions about future taxable income (loss) require significant judgment and are consistent with the plans and estimates we use to manage our businesses. A valuation allowance is established when it is more likely than not that some portion of the deferred tax asset will not be realized. The evaluation of a valuation allowance considers the character of the taxable income, ordinary income versus capital income. Tax benefits are recognized only for tax positions that are more likely than not to be sustained upon examination by tax authorities. The amount recognized is measured as the largest amount of benefit that is greater than 50% likely to be realized upon settlement. A liability for unrecognized tax benefits is recorded for any tax benefits claimed in our tax returns that do not meet these recognition and measurement standards. The effect of a change in tax rates is recognized in the period of enactment. If we were to be levied interest and penalties by the Internal Revenue Service, these amounts would be recognized as a component of income tax expense in the consolidated statements of operations. Our policy for recording interest and penalties associated with uncertain tax positions is to record such items as a component of tax expense. Stock-Based Compensation Stock-based compensation expense for equity instruments is measured based on the grant-date fair value of the awards. For stock option awards and purchase rights made under the 2019 Employee Stock Purchase Plan (the “ESPP”), the fair value is estimated on the date of grant using the Black-Scholes option-pricing valuation model. For restricted stock units (“RSUs”) and performance-based restricted stock units (“PSUs”), the fair value is equal to the closing price of our common stock on the date of grant. For awards with graded vesting and only service conditions, we recognize compensation costs on a straight-line basis over the requisite service period of the awards. For stock options and RSUs, the requisite service period is generally the award’s vesting period (typically four years ). PSUs vest upon the achievement of certain performance conditions and the provision of service with us through a specified period. Accruals of compensation cost for PSUs are based on the probable outcome of the performance conditions and are reassessed each reporting period. We recognize compensation cost for PSUs separately for each vesting tranche on a ratable basis over the requisite service period. The requisite service period for PSUs is based on an analysis of vesting requirements and performance conditions for the particular award. Certain employees are entitled to acceleration of vesting of a portion of their awards upon retirement, subject to age, service and notice requirements (“Retirement Policy”). Stock-based awards falling into the scope of the Retirement Policy are accounted for as a modification of existing awards under ASC Topic 718, Compensation – Stock Compensation . The modifications do not result in the recognition of incremental compensation cost, however, they do result in a new estimate of the requisite service period, which we reassess at each balance sheet date. For the ESPP, the requisite service period is generally the period of time from the offering date to the purchase date. Forfeitures are accounted for as they occur. Comprehensive (Loss) Income Comprehensive (loss) income is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. Comprehensive (loss) income is made up of net (loss) income plus net unrealized gain (loss) on marketable investment securities, which is our only other item of other comprehensive (loss) income. F-16 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Recently Adopted Accounting Pronouncements In December 2023, the FASB issued Accounting Standards Update (“ASU”) No. 2023-09, Income Taxes (Topic 740) — Improvements to Income Tax Disclosures (“ASU 2023-09”), which is intended to enhance the transparency and decision usefulness of income tax disclosures. The amendments in ASU 2023-09 provide for enhanced income tax information primarily through changes to the rate reconciliation and income taxes paid information. The guidance was effective for public entities for fiscal years beginning after December 15, 2024. We adopted ASU 2023-09 prospectively in fiscal year 2025 for the annual reporting period ending December 31, 2025. F or additional information on our tax disclosure, see Note 15. Accounting Pronouncements Yet to be Adopted In November 2024, the FASB issued ASU No. 2024-03, Income Statement—Reporting Comprehensive Income (Subtopic 220-40)—Expense Disaggregation Disclosures: Disaggregation of Income Statement Expenses (“ASU 2024-03”), which specifies additional disclosure requirements. The amendments in ASU 2024-03 require disclosure about the composition of certain income expense line items, such as purchases of inventory, employee compensation, and other expenses, as well as disclosure about selling expenses. The ASU is effective for fiscal years beginning after December 15, 2026, and interim periods beginning after December 15, 2027. Early adoption is permitted. We are currently evaluating the impact this update will have on the consolidated financial statements and disclosures. In July 2025, the FASB issued ASU No. 2025-05, Financial Instruments— Credit Losses (Topic 326): Practical Expedient for Certain Current Receivables (“ASU 2025-05”), which provides a practical expedient for estimating expected credit losses on current accounts receivable and contract assets arising from transactions under ASC 606. The practical expedient allows entities to assume that current conditions remain unchanged over the remaining life of the receivables. ASU 2025-05 is effective for annual periods beginning after December 15, 2025, including interim periods within those annual periods. Early adoption is permitted. We are currently evaluating the impact this update will have on the consolidated financial statements and disclosures. W e have evaluated all other recently issued, but not yet effective, accounting pronouncements and do not believe that these accounting pronouncements will have any material impact on the consolidated financial statements or disclosures upon adoption. 3. Revenue All of our revenues from contracts with customers are associated with the provision of testing services. Our revenues are primarily attributable to our DecisionDx®-Melanoma test for cutaneous melanoma, our TissueCypher® test for patients diagnosed with Barrett’s esophagus and our DecisionDx®-SCC test for cutaneous squamous cell carcinoma. We also provide our MyPath® Melanoma test for patients with melanocytic lesions, our DecisionDx®-UM test for uveal melanoma, and a pharmacogenomic testing service focused on mental health, IDgenetix®. Once we satisfy our performance obligations and bill for the service, the timing of the collection of payments may vary based on the payment practices of the third-party payor and the existence of contractually established reimbursement rates. The payments for our services are primarily made by third-party payors, including Medicare and commercial health insurance carriers. Certain contracts contain a contractual commitment of a reimbursement rate that differs from our list prices. However, absent a positive coverage policy, with or without a contractually committed reimbursement rate, with a commercial carrier or governmental program, our diagnostic tests may or may not be paid by these entities. In addition, patients do not enter into direct agreements with us that commit them to pay any portion of the cost of the tests in the event that their insurance provider declines to reimburse us. We may pursue, on a case-by-case basis, reimbursement from such patients in the form of co-payments and co-insurance, in accordance with the contractual obligations that we have with the insurance carrier or health plan. These situations may result in a delay in the collection of payments. F-17 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) The Medicare claims that are covered by Medicare are generally paid at a rate established on Medicare’s Clinical Laboratory Fee Schedule or by the respective Medicare contractor within 30 days from receipt. Medicare claims that were either submitted to Medicare prior to the local coverage determination or other coverage commencement date or are not covered but meet the definition of being medically reasonable and necessary pursuant to the controlling Section 1862(a)(1)(A) of the Social Security Act are generally appealed and may ultimately be paid at the first (termed “redetermination”), second (termed “reconsideration”) or third level of appeal ( de novo hearing with an Administrative Law Judge). A successful appeal at any of these levels may result in prompt payment. In the absence of Medicare coverage, contractually established reimbursement rates or other coverage, we have concluded that our contracts include variable consideration because the amounts paid by Medicare or commercial health insurance carriers may be paid at less than our standard rates or not paid at all, with such differences considered implicit price concessions. Variable consideration attributable to these price concessions is measured at the expected value using the “most likely amount” method under ASC 606. The amounts are estimated using historical average collection rates by test type and payor category taking into consideration the range of possible outcomes, the predictive value of our past experiences, the time period of when uncertainties expect to be resolved and the amount of consideration that is susceptible to factors outside of our influence, such as the judgment and actions of third parties. Such variable consideration is included in the transaction price only to the extent it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainties with respect to the amount are resolved. Variable consideration may be constrained and excluded from the transaction price in situations where there is no contractually agreed upon reimbursement coverage or in the absence of a predictable pattern and history of collectability with a payor. Accordingly, in such situations revenues are recognized on the basis of actual cash collections. Variable consideration for Medicare claims that are not covered by Medicare, including those claims undergoing appeal, is deemed to be fully constrained due to factors outside our influence (e.g., judgment or actions of third parties) and the uncertainty of the amount to be received is not expected to be resolved for a long period of time. Variable consideration is evaluated each reporting period and adjustments are recorded as increases or decreases in revenues. Included in revenues for the years ended December 31, 2025, 2024 and 2023 were $ 7.6 million, $ 1.8 million and $ 4.5 million of net negative revenue adjustments, respectively, associated with changes in estimated variable consideration related to performance obligations satisfied in previous periods. These amounts include (i) adjustments for actual collections versus estimated amounts and (ii) cash collections and the related recognition of revenue in current period for tests delivered in prior periods due to the release of the constraint on variable consideration. Because our contracts with customers have an expected duration of one year or less, we have elected the practical expedient in ASC 606 to not disclose information about our remaining performance obligations. Any incremental costs to obtain contracts are recorded as SG&A expenses as incurred due to the short duration of our contracts. Contract balances consisted solely of accounts receivable (both current and noncurrent) as of December 31, 2025 and 2024. Disaggregation of Revenues The table below provides the disaggregation of revenue by type (in thousands): Years Ended December 31, 2025 2024 2023 Dermatologic (1) $ 216,369 $ 256,996 $ 183,375 Non-Dermatologic (2) 127,860 75,073 36,413 Total net revenues $ 344,229 $ 332,069 $ 219,788 (1) Consists of DecisionDx-Melanoma, DecisionDx-SCC and MyPath Melanoma. (2) Consists of TissueCypher, DecisionDx-UM and IDgenetix. We have presented disaggregated net revenues included in our single reportable segment in the table above. The characteristics for each test in our single segment are similar, with each test having a single performance obligation. Our CODM is the single individual responsible for managing our segment and reviews consolidated results and budgets in assessing performance and in allocating resources. See Note 16 for additional information about our reportable segment. F-18 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Payor Concentration We rely upon reimbursements from third-party government payors (primarily Medicare) and private-payor insurance companies to collect accounts receivable related to sales of our tests. Our significant third-party payors and their related revenues, each of which accounted for more than 10% of total revenues or accounts receivable balances were as follows: Percentage of Revenues Percentage of Accounts Receivable (current) Percentage of Accounts Receivable (noncurrent) Years Ended December 31, As of December 31, As of December 31, 2025 2024 2023 2025 2024 2025 2024 Medicare 44 % 47 % 49 % 18 % 18 % * * Payor A 16 % 15 % 14 % 15 % 19 % 16 % 15 % Payor B * * * 22 % 20 % 10 % 12 % * Less than 10% 4. (Loss) Earnings Per Share Basic (loss) earnings per share is computed by dividing net (loss) income for the period by the weighted-average number of common shares outstanding during the period. Diluted (loss) earnings per share reflects the additional dilution from potential issuances of common stock, such as stock issuable pursuant to the exercise of stock options, vesting of RSUs and PSUs or purchases under the ESPP. The treasury stock method is used to calculate the potential dilutive effect of these common stock equivalents. Contingently issuable PSU awards are included in the computation of diluted (loss) earnings per share when the applicable performance criteria would be met and the common shares would be issuable if the end of the reporting period were the end of the contingency period. However, potentially dilutive shares are excluded from the computation of diluted (loss) earnings per share when their effect is antidilutive. The following table shows the computation of basic and diluted (loss) earnings per share (in thousands, except per share data): Years Ended December 31, 2025 2024 2023 Numerator: Net (loss) income $ ( 24,158 ) $ 18,245 $ ( 57,466 ) Denominator: Weighted-average common shares outstanding, basic 28,986 27,776 26,802 Assumed exercise of stock options — 457 — Assumed vesting of RSUs — 858 — Assumed vesting of PSUs — 144 — Assumed issuance of shares under the ESPP — 20 — Weighted-average common shares outstanding, diluted 28,986 29,255 26,802 (Loss) earnings per share: Basic $ ( 0.83 ) $ 0.66 $ ( 2.14 ) Diluted $ ( 0.83 ) $ 0.62 $ ( 2.14 ) F-19 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Due to the Company reporting a net loss attributable to common stockholders for years ended December 31, 2025 and 2023, all potentially dilutive securities are antidilutive and are excluded from the computations of diluted loss per share. The table below provides the weighted-average number of potential common shares associated with outstanding securities not included in our calculation of diluted (loss) earnings per share for the years ended December 31, 2025, 2024 and 2023 because to do so would be antidilutive. With regard to the PSUs, we assume that the associated performance targets will be met at the target level of performance for purposes of calculating diluted earnings per common share until such time that it is probable that actual performance will be above or below target (in thousands): Years Ended December 31, 2025 2024 2023 Stock options 2,913 2,445 3,319 RSUs and PSUs 4,084 531 3,350 ESPP 174 160 330 Total 7,171 3,136 6,999 In connection with our acquisition of AltheaDx, Inc. (“AltheaDx”) in April 2022, we agreed to pay up to an additional $ 75.0 million in cash and common stock upon the achievement of certain commercial milestones for the IDgenetix test during 2022, 2023 and 2024. The milestones required to trigger these additional payments were not met in any of those years. As a result, no cash payments were made, and no shares of common stock were issued or excluded from the calculation of diluted (loss) earnings per share during those years. 5. Marketable Investment Securities Marketable investment securities consisted of the following (in thousands): As of December 31, 2025 2024 Current marketable investment securities: Equity securities $ 5,555 $ 3,555 Debt securities - AFS 171,631 169,866 Debt securities - HTM (1) 5,590 — Total current marketable investment securities $ 182,776 $ 173,421 (1) We held no HTM debt securities as of December 31, 2024. Equity Securities The portion of unrealized gains related to equity securities still held during the period is as follows (in thousands): Years Ended December 31, 2025 2024 2023 Net gains on equity securities $ 1,466 $ 555 $ — Less: Net gain recognized on equity securities sold 484 — — Net unrealized gains recognized on equity securities still held $ 982 $ 555 $ — F-20 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Debt Securities The following tables present our debt securities (in thousands): December 31, 2025 Amortized Cost Unrealized Estimated Fair Value Gains Losses U.S. government securities - AFS $ 171,364 $ 269 $ ( 2 ) $ 171,631 U.S. government securities - HTM 5,590 11 — 5,601 Total debt securities $ 176,954 $ 280 $ ( 2 ) $ 177,232 December 31, 2024 Amortized Cost Unrealized Estimated Fair Value Gains Losses U.S. government securities - AFS $ 169,636 $ 244 $ ( 14 ) $ 169,866 U.S. government securities - HTM (1) — — — — Total debt securities $ 169,636 $ 244 $ ( 14 ) $ 169,866 (1) We held no HTM debt securities as of December 31, 2024. Our U.S. government securities includes both AFS and HTM securities. The AFS securities are available to be sold to meet operating needs or otherwise, but are generally held through maturity. We classify all AFS investments as current assets, as these are readily available for use in current operations. As of December 31, 2025 and 2024, all of our AFS securities had contractual maturities of one year or less. We classify our HTM investments as current assets, as we have the positive intent and ability to hold these investments to maturity, and all such maturities are less than one year from the balance sheet date. We evaluated our U.S. government securities under the AFS and HTM impairment model guidance, respectively, and determined our investment portfolio is comprised of low-risk, investment grade securities. For the years ended December 31, 2025, 2024 and 2023, the unrealized losses on our AFS and HTM U.S. government securities are not attributed to credit risk. We believe that an allowance for credit losses is unnecessary because the unrealized losses on certain of our marketable investment securities are due to market factors. The allowance for credit losses was zero as of December 31, 2025 and 2024. There were no realized gains or losses on sales of debt securities for the years ended December 31, 2025, 2024 and 2023. In addition, there were no credit-related or noncredit-related impairment losses recognized for the years ended December 31, 2025, 2024 and 2023. Accrued interest receivable for our AFS and HTM U.S. government securities is included in prepaid expenses and other current assets in the consolidated balance sheets. As of December 31, 2025 and 2024, the accrued interest receivable related to AFS securities was $ 1.1 million and $ 0.6 million, respectively. As of December 31, 2025, the accrued interest receivable related to HTM securities was immaterial. There were no amounts accrued as of December 31, 2024, as no securities were classified as HTM at that time. Additional information relating to the fair value of marketable investment securities can be found in Note 11. F-21 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) 6. Property and Equipment, Net Property and equipment, net consisted of the following (in thousands): As of December 31, 2025 2024 Land $ 7,245 $ 7,245 Lab equipment 33,034 23,633 Leasehold improvements 14,834 14,616 Computer equipment 5,920 5,306 Furniture and fixtures 3,648 3,541 Construction-in-progress 51,059 9,614 Total 115,740 63,955 Less: Accumulated depreciation ( 18,297 ) ( 12,833 ) Property and equipment, net $ 97,443 $ 51,122 Depreciation expense was recorded in the consolidated statements of operations as follows (in thousands): Years Ended December 31, 2025 2024 2023 Cost of sales (exclusive of amortization of acquired intangible assets) $ 3,916 $ 2,950 $ 1,758 Research and development 355 354 330 Selling, general and administrative 1,662 1,587 1,229 Total depreciation expense $ 5,933 $ 4,891 $ 3,317 7. Goodwill and Other Intangible Assets, Net Goodwill We had a single reportable segment consisting of a single operating segment where the operating segment and the single reporting unit were the same for the years ended December 31, 2025, 2024 and 2023, where all goodwill was allocated. As of December 31, 2025 and 2024, our goodwill balance was $ 10.7 million. See Note 16 for additional information on our reportable segment. We conducted annual impairment testing of goodwill in the fourth quarter which indicated the fair value of our reporting unit exceeded its carrying value by approximately 80 %. Therefore, no impairment was indicated for the year ended December 31, 2025. To measure the fair value of our single reporting unit, we used a market approach whereby we calculated our total market capitalization on the impairment test date, based on the closing price of our common stock as reported on the Nasdaq Global Market, and applied a reasonable control premium. The control premium was based on an analysis of control premiums paid in recent acquisitions of companies in the same or similar industry as us. No impairment charges were recorded against goodwill for the years ended December 31, 2025, 2024 and 2023. F-22 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Other Intangible Assets, Net Our other intangible assets, net consisted of the following (in thousands): As of December 31, 2025 Gross carrying value Accumulated amortization Net Weighted-Average Remaining Life (in years) Developed technology $ 153,500 $ ( 64,721 ) $ 88,779 10.3 Assembled workforce 563 ( 460 ) 103 0.9 Total other intangible assets, net $ 154,063 $ ( 65,181 ) $ 88,882 As of December 31, 2024 Gross carrying value Accumulated amortization Net Weighted-Average Remaining Life (in years) Developed technology $ 125,317 $ ( 29,996 ) $ 95,321 8.0 Assembled workforce 563 ( 347 ) 216 1.9 Total other intangible assets, net $ 125,880 $ ( 30,343 ) $ 95,537 The estimated future aggregate amortization expense as of December 31, 2025 was as follows (in thousands): Years Ending December 31, 2026 $ 9,019 2027 8,916 2028 8,941 2029 8,916 2030 8,916 Thereafter 44,174 Total $ 88,882 On December 1, 2024, we revised the estimated remaining useful life of our IDgenetix developed technology intangible asset, which resulted in our recognition of an additional $ 2.1 million in expense from amortization of acquired intangible assets, reducing net income by the same amount for the year ended December 31, 2024. During the first quarter of 2025, we decided to discontinue our IDgenetix test offering, effective May 2025. As a result, we revised the estimated useful life of the related intangible asset and fully amortized the asset as of March 31, 2025, resulting in an acceleration of amortization expense of approximately $ 20.1 million. In May 2025, in connection with the acquisition of Previse, and in accordance with ASC 805, we determined that substantially all of the fair value of the gross assets acquired was concentrated in a single identifiable asset; accordingly, the transaction was accounted for as an asset acquisition. The acquired intangible asset consists of developed technology with a fair value of $ 28.2 million, an estimated useful life of 12 years, and is amortized on a straight-line basis. Amortization expense of intangible assets was $ 34.8 million, $ 11.1 million and $ 9.0 million for the years ended December 31, 2025, 2024 and 2023, respectively. F-23 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) 8. Other Accrued and Current Liabilities Other accrued and current liabilities consisted of the following (in thousands): As of December 31, 2025 2024 Accrued service fees $ 3,213 $ 2,338 Clinical studies 2,674 2,580 ESPP Contributions 924 1,225 Other 2,126 1,850 Total $ 8,937 $ 7,993 9 . Long-Term Debt Our long-term debt consisted of the following (in thousands): As of December 31, 2025 2024 Term debt $ 10,200 $ 10,200 Unamortized discount ( 143 ) ( 177 ) Total debt, net 10,057 10,023 Less: Current portion of long-term debt ( 417 ) ( 278 ) Total long-term debt $ 9,640 $ 9,745 Future maturities of principal amounts on long-term debt as of December 31, 2025 were as follows (in thousands): Years Ending December 31, 2026 $ 417 2027 5,000 2028 4,583 Total $ 10,000 2024 Loan and Security Agreement On March 26, 2024 (the “Closing Date”), we entered into a Loan and Security Agreement, as amended in April 2025 (the “2024 LSA”), by and between us, our wholly owned subsidiary, Castle Narnia Real Estate Holding 1, LLC and Silicon Valley Bank, a division of First-Citizens Bank & Trust Company (the “Lender”). The 2024 LSA provides for a term loan in the principal amount of $ 10.0 million, which was drawn on the Closing Date (the “2024 Term Loan”) and provided for a $ 25.0 million line of credit that was available at our option from the Closing Date through September 30, 2025, with the same interest rate and maturity as the 2024 Term Loan (the “2024 Credit Line”). The Consent and First Amendment executed on April 4, 2025, modified certain terms of the 2024 LSA, including the extension of the draw period for the 2024 Credit Line from March 31, 2025 to September 30, 2025, which expired on September 30, 2025, the 2024 Credit Line expired as discussed below. The obligations under the 2024 LSA are secured by substantially all of our assets, excluding intellectual property, the real property held by the Company, and are subject to certain other exceptions and limitations. We have the right to prepay the 2024 LSA in whole, subject to a prepayment fee of approximately 1.50 % if paid prior to March 26, 2026. Amounts repaid may not be reborrowed. F-24 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) The 2024 LSA contains customary conditions of borrowing, events of default and covenants, including covenants that restrict our ability to dispose of assets, merge with or acquire other entities, incur indebtedness and make distributions to holders of our capital stock. Should an event of default occur, including the occurrence of a material adverse change, we could be liable for immediate repayment of all obligations under the 2024 LSA. Should we seek to further amend the terms of the 2024 LSA, the consent of the Lender would be required. As of December 31, 2025, we were in compliance with all of the covenants. The 2024 LSA bears interest at a floating rate equal to the greater of (a) the WSJ Prime Rate plus 0.25 % or (b) 6.00 % per annum. The 2024 Term Loan was interest-only from the Closing Date through November 30, 2025, subject to extension under the Interest-Only Extension Milestone provision (as defined in the 2024 LSA). On August 26, 2025, we elected to extend the interest-only period to December 1, 2026. Beginning in December 2026, the principal payments will be made in equal monthly installments through the maturity date of November 1, 2028. In addition, we are required to make a final payment equal to 2.00 % of the aggregate original principal amounts of the 2024 Term Loan, due at maturity or upon full repayment. 2024 Term Loan On the Closing Date, we drew $ 10.0 million under the 2024 Term Loan. We are obligated to make a final payment of $ 0.2 million under the terms of the 2024 LSA final payment provisions. A discount on debt equal to this obligation was recorded on the draw date and is being amortized as additional interest expense using the effective interest method over the term of the debt. As of December 31, 2025, no principal payments have been made and the weighted-average effective interest rate for all outstanding debt under the 2024 Term Loan was 7.69 %. 2024 Credit Line We had a $ 25.0 million line of credit under the 2024 Line of Credit, from the Closing Date through September 30, 2025. The 2024 Credit Line expired on September 30, 2025 and no amounts were drawn during the term. Interest Expense on Long-Term Debt Interest expense on long-term debt consisted of the following (in thousands): Years Ended December 31, 2025 2024 Interest expense on long-term debt $ 807 $ 685 Less: Capitalized interest ( 758 ) ( 180 ) Total $ 49 $ 505 There was no interest expense on long-term debt or capitalized interest for the year ended December 31, 2023. 10. Leases Operating Leases We lease office space in Friendswood, Texas (the “Friendswood Lease”) which previously served as our corporate headquarters before moving in January 2026. The Friendswood Lease commenced in late 2020 under a 60-month term and, under a subsequent amendment, now expires in March 2026. We lease two facilities in Phoenix, Arizona for laboratory and office space under two agreements with terms expiring in July 2033 and February 2034, respectively. Each contract provides two five-year renewal options. We lease general office and laboratory facilities in Pittsburgh Pennsylvania (the “Pittsburgh Lease”). The Pittsburgh Lease commenced in April 2023 under a term of 10.5 years, and with a five-year renewal option and an early termination clause. The lease was originally executed in April 2022. F-25 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) We lease general office and laboratory facilities in Scottsdale, Arizona (the “Scottsdale Lease”). On May 14, 2025, we entered into a lease agreement (the “Scottsdale Commencement Date”) with Perimeter Gateway Portfolio, LLC (the “Lessor”) for approximately 55,573 square feet. The Scottsdale Lease has a term of 143 months that will expire in April 2037, and provides a right of refusal to lease any additional adjacent space that may become available. The Scottsdale Lease includes two optional five-year term extensions, and a one -time option to terminate the lease on the last day of the 96 th month following the Scottsdale Commencement Date, subject to certain conditions, in exchange for early termination fee. The fee would equal the unamortized balance of commissions paid to the Lessor’s broker and our broker, plus the amortized balance of hard and soft costs incurred by the Lessor in connection with the tenant improvement allowance. The Scottsdale Lease also provides for $ 7.2 million in lease incentives in form of Lessor-paid improvements. Rent for the first twelve months is abated, totaling $ 1.8 million, with any unamortized amounts becoming payable in the event of a default under the lease. We have not included the optional renewal periods in the measurement of the lease obligations because it is not reasonably certain that we will exercise these renewal options. Our other operating leases primarily consist of office equipment. Finance Lease We lease office printers and other office equipment (the “Finance Leases”) for use across our facilities, which expire in 2029. Certain of our Finance Leases contain automatic one year extensions that become effective unless we provide advanced notice of our intent not to extend the term. In 2025, we received a cash lease incentive of $ 0.2 million for certain Finance Leases. There were no cash lease incentives received in 2024 or 2023. Discount Rates We discount our lease obligations using our incremental borrowing rate as of the lease commencement date or, for lease modifications, as of the effective date of the modification. The incremental borrowing rate represents the rate of interest we would expect to pay to borrow on a collateralized basis over a similar term in an amount equal to the lease payments in a similar economic environment. Beginning March 26, 2024, we had outstanding borrowings under the 2024 LSA and used the interest rate on those borrowings to determine our incremental borrowing rate for lease measurement. We then adjust our incremental borrowing rate for the economic environment, collateral and other information available at the lease commencement date to develop a discount rate appropriate for each lease. Prior to having outstanding borrowings under the 2024 LSA, we primarily considered industry data, our credit rating and the lease term to determine our incremental borrowing rate. Lease Balances and Costs Lease balances reflected in the consolidated balance sheets were as follows (in thousands): As of December 31, Lease Balance Classification 2025 2024 Lease Assets Operating Operating lease assets $ 14,795 $ 11,584 Finance Property and equipment, net $ 251 $ 222 Lease Liabilities Current Operating Operating lease liabilities $ 1,325 $ 1,665 Finance Other accrued and current liabilities $ 102 $ 101 Noncurrent Operating Noncurrent operating lease liabilities $ 25,217 $ 14,345 Finance Noncurrent finance lease liabilities $ 314 $ 311 F-26 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Lease costs included in the consolidated statements of operations were as follows (in thousands): Years Ended December 31, 2025 2024 2023 Operating lease cost (1) $ 3,980 $ 2,933 $ 2,625 Finance lease cost Amortization of lease assets 91 87 141 Interest on finance lease liabilities 37 23 11 Short-term lease cost 26 6 108 Total lease cost $ 4,134 $ 3,049 $ 2,885 (1) Includes variable lease cost of $ 0.7 million, $ 0.4 million and $ 0.3 million for the years ended December 31, 2025, 2024 and 2023, respectively. Other Information Supplemental cash flow information for lease activities included in the consolidated statements of cash flows were as follows (in thousands): Years Ended December 31, 2025 2024 2023 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 3,150 $ 2,657 $ 1,723 Operating cash flows from interest paid on finance leases $ 37 $ 20 $ 11 Financing cash flows from finance leases $ 115 $ 97 $ 142 The weighted-average remaining lease term and weighted-average discount rates used were as follows: As of December 31, 2025 2024 Weighted-average remaining lease term (years) Operating leases 9.4 8.5 Finance leases 3.8 4.5 Weighted-average discount rate Operating leases 8.2 % 8.4 % Finance leases 8.2 % 8.4 % F-27 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Future maturities for operating lease and finance lease liabilities as of December 31, 2025 were as follows (in thousands): Operating Leases Finance Leases Years Ending December 31, 2026 $ 2,503 $ 129 2027 3,629 129 2028 4,303 129 2029 4,396 97 2030 4,489 — Thereafter 20,104 — Total lease payments 39,424 484 Less: Interest component ( 12,882 ) ( 68 ) Present value of lease payments $ 26,542 $ 416 Undiscounted future lease payments for leases that had not yet commenced as of December 31, 2025 was zero . 11. Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market in an orderly transaction between market participants at the measurement date. The fair value hierarchy prioritizes the inputs to valuation techniques used in measuring fair value. There are three levels to the fair value hierarchy based on the reliability of inputs, as follows: Level 1 – Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2 – Inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 3 – Unobservable inputs in which little or no market data exists, therefore requiring us to develop our own assumptions. Financial instruments measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. For equity securities traded on foreign exchanges, fair values are determined based on quoted market prices in the applicable foreign markets and are remeasured into U.S. dollars using exchange rates in effect at each balance sheet date in accordance with ASC 830. The use of different assumptions, exchange rates and/or estimation methodologies may have a material effect on estimated fair values. Accordingly, the fair value estimates disclosed, or amounts recorded may not be indicative of the amount that we or holders of the instruments could realize in a current market exchange. F-28 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) The tables below provide information by level within the fair value hierarchy, of our financial assets and liabilities that are accounted for at fair value on a recurring basis (in thousands): As of December 31, 2025 Quoted Prices in Active Markets for Identical Items (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Money market funds (1) $ 108,914 $ — $ — $ 108,914 U.S. government securities - AFS (2) $ 171,631 $ — $ — $ 171,631 Equity securities (2) $ 5,555 $ — $ — $ 5,555 Liabilities Term Debt (3)(4) $ — $ 10,057 $ — $ 10,057 As of December 31, 2024 Quoted Prices in Active Markets for Identical Items (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Money market funds (1) $ 114,091 $ — $ — $ 114,091 U.S. government securities - AFS (2) $ 169,866 $ — $ — $ 169,866 Equity securities (2) $ 3,555 $ — $ — $ 3,555 Liabilities Term Debt (3)(4) $ — $ 10,023 $ — $ 10,023 (1) Classified as “Cash and cash equivalents” in the consolidated balance sheets. (2) Classified as “Marketable investment securities” in the consolidated balance sheets. (3) Classified as “Current portion of long-term debt” and “Long-term debt” in the consolidated balance sheets. (4) Borrowings approximate their fair value as the interest rate is variable and reflects market rates. We have U.S. government securities that are HTM investments and are carried at amortized costs. The fair value of our HTM investments is classified as Level 1 of the fair value hierarchy. For additional information on the carrying amount and fair value of our HTM investments, see Note 5. The Convertible Loan Receivable with SciBase is carried at amortized cost which approximates fair value due to the variable interest rate and market-based terms of the instrument. Fair value is estimated using a discounted cash flow model. The inputs used to fair value the Convertible Loan Receivable are classified as Level 2 in the fair value hierarchy and include three-month STIBOR and a market credit spread. For additional information on the carrying amount and estimated fair value of our Convertible Loan Receivable, see Note 2. F-29 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) 12. Commitments and Contingencies From time to time, we may be involved in legal proceedings arising in the ordinary course of business. On February 1, 2024, we received a subpoena from the Department of Health and Human Services, Office of Inspector General, seeking documents and information concerning claims submitted for payment under federal healthcare programs. The subpoena requested that we produce documents relating primarily to interactions with medical providers and billing to government-funded healthcare programs for our tests. The time period covered by the subpoena is January 1, 2015 through February 1, 2024. We are continuing to cooperate with the government’s request and are in the process of responding to the subpoena. We are unable to predict what action, if any, might be taken in the future by the Department of Health and Human Services, Office of Inspector General, or any other governmental authority as a result of the matters related to this subpoena. No claims have been made against us at this time. Any potential claims could subject us to significant liability for damages and harm our reputation. Our insurance and indemnities may not cover all claims that may be asserted against us. We are unable to predict the outcome and are unable to make a meaningful estimate of the amount or range of loss, if any, that could result from any unfavorable outcome. In November 2025, we entered into a subscription agreement in connection with SciBase’s proposed rights offering. Under the agreement, we are committed to subscribe for its pro rata share of shares issuable under the rights offering and, if requested by SciBase, to subscribe for up to an additional 115.0 million shares. The subscription commitment is subject to an ownership limitation such that our ownership interest in SciBase may not reach or exceed 20 % of the outstanding shares following the offering. The rights offering was completed in January 2026, see Note 17. 13. Stockholders’ Equity Capital Stock Our Amended and Restated Certificate of Incorporation, dated July 29, 2019, authorizes us to issue up to 200,000,000 shares of common stock with a par value of $ 0.001 per share. We are also authorized to issue up to 10,000,000 shares of preferred stock with a par value of $ 0.001 per share. No dividends were declared or paid during the years ended December 31, 2025 or 2024. 14. Stock Incentive Plans and Stock-Based Compensation Equity Incentive Plans On July 24, 2019, we adopted the 2019 Equity Incentive Plan (the “2019 Plan”). As of December 31, 2025, there were 1,279,290 shares remained available for grant under the 2019 Plan. The 2019 Plan provides for automatic annual increases to the number of shares authorized for issuance, equal to 5 % of our common shares outstanding as of the immediately preceding year end, through January 1, 2029. Under this provision, effective January 1, 2026, an additional 1,484,315 shares became available under the 2019 Plan. Prior to adopting the 2019 Plan, we had adopted the 2008 Stock Plan (the “2008 Plan”) on September 6, 2008 and the 2018 Stock Plan (the “2018 Plan”) on August 15, 2018. No additional shares have been issued from each respective plan following the chronological adoption of each succeeding plan. Our stock incentive plans provide for the granting of awards to employees, directors and consultants. Available awards under our incentive plans include options to purchase common stock as well as RSU, PSUs and other equity-based awards providing recipients the right to receive common shares. Inducement Plan On December 22, 2022, our board of directors approved the 2022 Inducement Plan (the “Inducement Plan”). The Inducement Plan provides for the granting of awards as inducement material to the grantee’s entering into employment with us to the extent such grantee was not previously an employee of ours or is entering into employment following a bona fide period of non-employment with us. On August 5, 2025, our compensation committee amended the Inducement Plan to increase the number of shares issuable under the Inducement Plan by 700,000 shares. As of December 31, 2025, there were 718,454 shares available for grant under the amended Inducement Plan. F-30 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Options Granted Under our Plans Our 2019 Plan and Inducement Plan provide for the granting of options in form of incentive stock options (“ISO”) and non-statutory stock options (“NSOs”). ISOs may only be granted to our employees and employee-directors. NSOs may be granted to our employees, employee-directors, nonemployee directors and consultants. Options may be granted for terms up to ten years from the date of grant, as determined by the board of directors; provided, however, that with respect to an ISO granted to a person who owns stock representing more than 10 % of the voting power of all classes of stock of ours, the terms shall be for no more than five years from the date of grant. The exercise price of options granted must be no less than 100 % of the fair market value of the shares on the date of grant, provided, however, that with respect to an ISO granted to an employee who at the time of grant of such options owns stock representing more than 10 % of the voting power of all classes of stock of ours, the exercise price shall not be less than 110 % of the fair market value of the shares on the date of grant. Options generally vest over four years (generally 25 % after one year and monthly thereafter), subject to the option holder’s continued service with us. We issue new shares to satisfy option exercises. Stock Options The following table summarizes our stock option activity: Weighted-Average Stock Options Outstanding Exercise Price Remaining Contractual Term (Years) Aggregate Intrinsic Value (in thousands) Balance as of January 1, 2023 3,419,840 $ 35.11 Granted 170 $ 25.06 Exercised ( 71,525 ) $ 3.77 Forfeited/Cancelled ( 139,506 ) $ 44.87 Balance as of December 31, 2023 3,208,979 $ 35.38 Granted 3,379 $ 71.22 Exercised ( 135,875 ) $ 14.85 Forfeited/Cancelled ( 86,720 ) $ 39.74 Balance as of December 31, 2024 2,989,763 $ 36.23 Granted — $ — Exercised ( 108,458 ) $ 20.34 Forfeited/Cancelled ( 96,873 ) $ 45.51 Balance as of December 31, 2025 2,784,432 $ 36.53 4.6 $ 24,372 Exercisable as of December 31, 2025 2,779,739 $ 36.55 4.6 $ 24,306 Restricted Stock Units RSUs represent the right to receive shares of our common stock at a specified future date, subject to vesting. Our RSUs generally vest annually from the grant date in four equal installments subject to the holder’s continued service with us. We issue new shares of common stock upon the vesting of RSUs. F-31 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) The following table summarizes our RSU activity: Restricted Stock Units Outstanding Weighted-Average Grant Date Fair Value Balance as of January 1, 2023 3,477,922 $ 27.56 Granted 549,296 $ 17.92 Vested (1) ( 901,547 ) $ 28.85 Forfeited/Cancelled ( 320,596 ) $ 25.62 Balance as of December 31, 2023 2,805,075 $ 25.48 Granted 1,708,028 $ 22.37 Vested (1) ( 982,403 ) $ 27.68 Forfeited/Cancelled ( 334,476 ) $ 21.79 Balance as of December 31, 2024 3,196,224 $ 23.52 Granted 1,715,247 $ 22.65 Vested (1) ( 1,237,950 ) $ 25.38 Forfeited/Cancelled ( 277,759 ) $ 23.38 Balance as of December 31, 2025 3,395,762 $ 22.42 (1) The aggregate number of shares withheld upon vesting for employee tax obligations was 366,776 , 281,275 and 254,197 for the years ended December 31, 2025, 2024 and 2023, respectively. Performance-Based Restricted Stock Units PSUs represent the right to receive shares of our common stock contingent upon the achievement of certain financial performance measures. We issue new shares of common stock upon the vesting of PSUs. On August 9, 2024 (the “Initial Vesting Date”), the board of directors certified that the revenue goal for the PSUs granted on December 23, 2022 (“2022 PSUs”) was achieved. Therefore, 50 % of the 2022 PSUs were vested and we immediately recognized approximately $ 0.1 million of stock-based compensation related to this performance metric. The remaining 50 % of the 2022 PSUs were subject to time-based vesting and vested in full on August 9, 2025. F-32 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) The following table summarizes our PSU activity: Performance-Based Restricted Stock Units Outstanding Weighted-Average Grant Date Fair Value Balance as of January 1, 2023 196,033 $ 23.23 Granted — $ — Vested — $ — Forfeited/Cancelled — $ — Balance as of December 31, 2023 196,033 $ 23.23 Granted 177,513 $ 21.23 Vested (1) ( 98,018 ) $ 23.23 Forfeited/Cancelled — $ — Balance as of December 31, 2024 275,528 $ 21.94 Granted 172,631 $ 22.23 Vested (1) ( 98,015 ) $ 23.23 Forfeited/Cancelled — $ — Balance as of December 31, 2025 350,144 $ 21.72 (1) The aggregate number of shares withheld upon vesting for employee tax obligations was 35,426 and 30,046 for the years ended December 31, 2025 and 2024, respectively . Employee Stock Purchase Plan The ESPP became effective July 24, 2019. Offerings under the ESPP are generally 24 months in length with four six-month purchase periods unless terminated earlier, as described below. Eligible employees who enroll in an offering are able to purchase shares of our common stock at a discount through payroll deductions, subject to certain limitations. The purchase price of the shares of common stock is the lesser of (i) 85 % of the fair market value of such shares on the offering date and (ii) 85 % of the fair market value of such shares on the purchase date. A new offering begins approximately every six months . Offerings are concurrent, but in the event the fair market value of a share of common stock on the first day of any purchase period during an offering (the “New Offering”) is less than or equal to the fair market value of a share of common stock on the offering date for an ongoing offering (the “Ongoing Offering”), then the Ongoing Offering terminates immediately following the purchase of shares on the purchase date immediately preceding the New Offering and the participants in the terminated Ongoing Offering are automatically enrolled in the New Offering. In such case, we account for this event as a modification of the Ongoing Offering. Notwithstanding the above, our board of directors (or an authorized committee thereof) may modify the terms of or suspend any future offerings prior to their commencement. As of December 31, 2025, 1,170,613 shares remained available for issuance under the ESPP. The ESPP provides for certain automatic increases in the number of shares of common stock reserved for issuance, which resulted in an additional 296,863 shares becoming available under the ESPP effective January 1, 2026. We issue new shares to satisfy the ESPP purchases. Determining Fair Value - Summary of Assumptions We use the closing price of our common stock on the date of grant to determine the fair value of RSUs and PSUs. We use the Black-Scholes option-pricing model to estimate the fair value of stock options and purchase rights issued under the ESPP at the date of grant, start of the offering or other relevant measurement date. Set forth below is a description of the significant assumptions used: • Expected term . The expected term is the period of time that granted options are expected to be outstanding. For stock options, we have set the expected term using the simplified method based on the weighted-average of both the period to vesting and the period to maturity for each option, as we have concluded that its stock option exercise history does not provide a reasonable basis upon which to estimate the expected term. For the ESPP, the expected term is the period of time from the offering date to the purchase date. F-33 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) • Expected volatility . For our ESPP, we estimate expected volatility based on the historical volatility of our common stock. For stock options, we previously estimated expected volatility using the historical stock prices of a group of comparable companies, together with our own stock price on a relative basis, due to the limited period during which our common stock had been actively traded. Beginning in the third quarter of 2025, our common stock established a sufficient trading history and, therefore, we use solely the historical volatility of our own stock in determining expected volatility. • Risk-free interest rate . We base the risk-free interest rate used in the Black-Scholes valuation model on the market yield in effect at the time of option grant and at the offering date for the ESPP, provided from the Federal Reserve Board’s Statistical Releases and historical publications from the Treasury constant maturities rates for the equivalent remaining terms. • Dividend yield . We have not paid, and do not have plans to pay, cash dividends. Therefore, we use an expected dividend yield of zero in the Black-Scholes option valuation model. The fair value of our common stock is also an assumption used to determine the fair value of stock options. The fair value of our common stock is the closing selling price per share of its common stock as reported on the Nasdaq Global Market on the date of grant or other relevant determination date. We use the Black-Scholes option pricing model to estimate the fair value of each option grant on the date of grant or any other measurement date. The following table sets forth the assumptions used to determine the fair value of stock options: Years Ended December 31, 2025 (1) 2024 2023 Average expected term (years) N/A 5.0 5.0 Expected stock price volatility N/A 80.20 % - 80.20 % 75.57 % - 76.01 % Risk-free interest rate N/A 4.39 % - 4.39 % 3.57 % - 3.57 % Dividend yield N/A — % — % (1) For the year ended December 31, 2025, no stock options were granted. The following table sets forth assumptions used to determine the fair value of the purchase rights issued under the ESPP: Years Ended December 31, 2025 2024 2023 Average expected term (years) 1.2 1.2 1.3 Expected stock price volatility 56.55 % - 85.21 % 59.85 % - 105.39 % 72.80 % - 130.95 % Risk-free interest rate 3.52 % - 4.22 % 3.82 % - 5.14 % 4.74 % - 5.33 % Dividend yield — % — % — % Fair Value and Intrinsic Value For the year ended December 31, 2025, no stock options were granted. For the years ended December 31, 2024 and 2023 the weighted-average grant date fair value of stock options was $ 9.23 and $ 15.99 per option, respectively. For the years ended December 31, 2025, 2024 and 2023 the weighted-average grant date fair value of the purchase rights issued under the ESPP was $ 9.71 , $ 12.66 and $ 11.43 per share, respectively. The aggregate intrinsic value of stock options exercised during the years ended December 31, 2025, 2024 and 2023 was $ 1.2 million, $ 1.7 million and $ 1.3 million, respectively. The aggregate intrinsic value of shares issued under the ESPP was $ 0.9 million, $ 1.0 million and $ 0.5 million during the years ended December 31, 2025, 2024 and 2023, respectively. The aggregate fair value of RSUs that vested during the years ended December 31, 2025, 2024 and 2023 was $ 36.1 million, $ 27.7 million and $ 18.1 million, respectively. F-34 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Stock-Based Compensation Expense Stock-based compensation expense is included in the consolidated statements of operations as follows (in thousands): Years Ended December 31, 2025 2024 2023 Cost of sales (exclusive of amortization of acquired intangible assets) $ 5,666 $ 5,529 $ 4,938 Research and development 7,555 9,598 10,119 Selling, general and administrative 32,672 35,193 36,162 Total stock-based compensation expense $ 45,893 $ 50,320 $ 51,219 Included in total stock-based compensation expense for the years ended December 31, 2025, 2024 and 2023 is $ 0.7 million, $ 0.7 million and $ 1.6 million, respectively, from the accelerated recognition of expense for modifications of awards falling in scope of the Retirement Policy. No tax benefits related to stock-based compensation expense were recorded in the consolidated statements of operations during the years ended December 31, 2025, 2024 and 2023 due to the valuation allowance on net deferred tax assets. As of December 31, 2025, the total unrecognized stock-based compensation cost related to outstanding awards was $ 64.7 million, which is expected to be recognized over a weighted-average period of 2.4 years. The total unrecognized compensation cost will be adjusted for forfeitures in future periods as they occur. 15. Income Taxes The components of income tax (benefit) expense are as follows (in thousands): Years Ended December 31, 2025 2024 2023 Current tax expense U.S. federal $ ( 254 ) $ 663 $ — State and local 1,126 1,255 324 Total current 872 1,918 324 Deferred tax benefit U.S. federal ( 6,081 ) 1,622 33 State and local ( 147 ) ( 221 ) ( 256 ) Total deferred ( 6,228 ) 1,401 ( 223 ) Total income tax (benefit) expense $ ( 5,356 ) $ 3,319 $ 101 F-35 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) The differences between income taxes expected at the U.S. federal statutory rate (21%) and the reported income tax benefit, following the adoption of ASU 2023-09, are summarized as follows (in thousands): Year Ended December 31, 2025 $ % Pre-tax loss $ ( 29,514 ) U.S. federal statutory income tax rate ( 6,199 ) 21.0 % State and local income taxes, net of federal effect 742 ( 2.5 ) % Tax credits: R&D tax credit ( 2,078 ) 7.0 % Non-taxable and non-deductible items: Non-deductible meals and entertainment 2,032 ( 6.9 ) % Stock-based compensation 2,374 ( 8.0 ) % Other 119 ( 0.4 ) % Change in valuation allowance ( 2,401 ) 8.1 % Other 55 ( 0.2 ) % Income tax benefit $ ( 5,356 ) 18.1 % The differences between income taxes expected at the U.S. federal statutory rate (21%) and the reported income tax expense, prior to the adoption of ASU 2023-09, are summarized as follows (in thousands): Years Ended December 31, 2024 2023 Pre-tax income (loss) $ 21,564 $ ( 57,365 ) U.S. federal taxes at statutory rate 4,528 ( 12,046 ) State income taxes 683 925 R&D tax credit ( 3,381 ) ( 2,186 ) Change in valuation allowance ( 4,469 ) 5,207 Stock-based compensation 1,528 4,323 Non-deductible officers’ compensation 2,651 2,377 Permanent differences 1,712 1,474 Other 67 27 Income tax expense $ 3,319 $ 101 F-36 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Income taxes paid (net of refunds) that exceed 5% of total income taxes paid (net of refunds) by jurisdictions following the adoption of ASU 2023-09, are as follows (in thousands): Year Ended December 31, 2025 U.S. federal $ 1,172 State and local Michigan 127 Pennsylvania 244 Virginia ( 138 ) Other 196 Total income taxes paid, net of refunds received $ 1,601 Significant components of deferred tax assets and liabilities are as follows (in thousands): As of December 31, 2025 2024 Deferred tax assets: NOL carryforwards $ 33,831 $ 31,782 Accrued liabilities 10,048 7,301 Capitalized R&D costs 8,925 15,485 Lease liabilities 7,050 3,774 Stock-based compensation 6,464 5,128 R&D tax credit 13,002 9,747 Total deferred tax assets 79,320 73,217 Less valuation allowance ( 48,662 ) ( 50,536 ) Deferred tax assets, net $ 30,658 $ 22,681 Deferred tax liabilities: Prepaid expenses $ ( 213 ) $ ( 185 ) Property and equipment ( 8,457 ) ( 6,374 ) Intangible assets ( 18,032 ) ( 14,986 ) ROU assets ( 5,654 ) ( 2,558 ) Other ( 637 ) ( 185 ) Total deferred tax liabilities ( 32,993 ) ( 24,288 ) Net deferred tax liability $ ( 2,335 ) $ ( 1,607 ) On July 4, 2025, the One Big Beautiful Bill Act (“OBBBA”) was enacted into law. The OBBBA includes a broad range of tax reform provisions affecting businesses, including reinstatement of permanent expensing of domestic research and development costs, higher EBITDA cap on the deduction for interest expense and 100% bonus depreciation. We will benefit from the reinstatement of permanent expensing of domestic research and development costs and 100% bonus depreciation. As of December 31, 2025, we had federal NOL carryforwards of approximately $ 134.8 million of which $ 52.9 million will begin to expire in 2032 if not utilized to offset taxable income, and $ 81.9 million may be carried forward indefinitely. Future changes in ownership, as defined by Section 382 of the IRC, could limit the amount of NOL carryforwards used in any one year. As of December 31, 2025, we had state NOL carryforwards of approximately $ 113.0 million, which begin to expire in 2030 if not utilized to offset state taxable income. As of December 31, 2025, we had $ 13.0 million of R&D tax credit carryforwards, including $ 1.4 million of state credits. These credits begin to expire in 2037 if not utilized to offset federal income tax liabilities. F-37 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) In general, under Section 382 and 383 of the IRC, a corporation that undergoes an “ownership change” is subject to limitations on its ability to utilize its pre-change NOLs and certain tax credits, to offset future taxable income and tax. In general, an ownership change occurs if the aggregate stock ownership of certain stockholders changes by more than 50 percentage points over such stockholders’ lowest percentage of ownership during the testing period (generally three years). We performed a Section 382 analysis from inception through the year ended December 31, 2025 and concluded we had experienced an ownership change in 2011, 2014 and 2020. These changes in ownership did not result in the expiration of any NOLs or R&D credits. However, future changes in ownership may further limit our ability to utilize our NOL carryforwards and R&D tax credit carryforwards. We have also performed Section 382 analyses with respect to the NOLs we obtained in our acquisitions of Cernostics, AltheaDx and Previse. Based on changes in ownership that have occurred, $ 36.3 million of NOLs relating to Cernostics and AltheaDx and zero relating to Previse are expected to expire unused as a result of Section 382 limitations. With respect to Previse, we acquired $ 2.3 million of NOLs that can be carried forward indefinitely to offset future taxable income. As of December 31, 2025 and 2024, we placed a valuation allowance of $ 48.7 million and $ 50.5 million, respectively, against our net deferred tax asset balance, as we have determined that it is more likely than not that they will not be realized. The valuation allowance as of December 31, 2025 and 2024 was primarily related to NOL and R&D tax credit carryforwards that more likely than not, will expire unused. The net change in total valuation allowance for each of the years ended December 31, 2025, 2024 and 2023 was a decrease of $ 1.9 million, a decrease of $ 4.5 million, and an increase of $ 5.1 million, respectively. We assessed whether we had any significant uncertain tax positions related to open tax years and concluded there were none. Accordingly, no reserve for uncertain tax positions has been recorded as of December 31, 2025 and 2024. We are generally no longer subject to tax examinations for U.S. federal income tax purposes for fiscal years prior to 2022 and fiscal years prior to 2021 for multiple state jurisdictions. However, since we have been in an NOL position since 2008 until recently, our 2008 to 2021 federal tax returns and our 2008 to 2020 state tax returns are potentially subject to examination adjustments to the extent of those NOL carryforwards. We are currently under IRS audit for fiscal year 2023. We believe our provisions for income taxes is adequate; however, any assessment may affect our results of operations and cash flows. No material amounts of tax-related interest or penalties were recorded during the years ended December 31, 2025, 2024 and 2023. 16. Segment and Related Information The Company derives revenues through the delivery of test reports for our molecular diagnostic tests. Clinicians use the results from these tests to aid in the diagnosis and treatment of dermatologic cancers, Barrett’s esophagus, uveal melanoma and in the treatment of mental health conditions. All of our operations are located within the United States (“U.S.”) and our business is focused on the U.S. market. Budgets and financial information for net revenues are maintained and are regularly reviewed for each of our tests but expense information is not maintained and readily available below the consolidated results of operations level of aggregation. We have a single reportable segment consisting of a single operating segment where our CEO is our CODM, which aligns with how our business is organized and is managed. The accounting policies and measurements of income before income taxes and discontinued operations for the consolidated financial statements and the reportable segment are the same. The CODM assesses segment performance using actual-to-actual and actual-to-budget variance analysis for segment net revenues, significant segment expenses and net income to assess segment performance and in deciding how to allocate resources. F-38 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) The measures of segment loss or profit for of our single reportable segment were as follows (in thousands): Years Ended December 31, 2025 2024 2023 Net revenues from external customers (1) $ 344,229 $ 332,069 $ 219,788 Significant segment expenses: Personnel costs 209,816 189,883 172,248 Organizational and marketing costs 51,545 44,178 39,481 Inventory usage 21,821 19,930 15,475 Clinical studies and publication costs 8,777 9,951 11,924 Professional services 10,928 10,476 7,496 Other segment items 65,500 39,406 30,630 Segment (loss) profit $ ( 24,158 ) $ 18,245 $ ( 57,466 ) (1) For information on disaggregation of segment revenue by type and information about payor concentration, see Note 3. Significant Segment Expenses Personnel Costs Personnel costs consist of salaries and wages, bonuses, employee benefits, stock-based compensation expense and payroll taxes. Personnel costs are a significant portion of operating expenses and are a component of cost of sales, R&D expense and SG&A expense. Our CODM considers this information injunction with test report deliveries in assessing budgeted and actual operational performance and in allocating resources. Organizational and Marketing Costs Organizational and marketing costs include expense incurred for travel, transportation, meals and lodging, training and conference and venue fees and are a component of cost of sales, R&D expense and SG&A expense. Our CODM considers this information in their assessment of operating expense results and in planning and budgeting for future corporate organizational and marketing activities. Inventory Usage Inventory usage is the expense incurred through direct materials used in processing our tests, and are significant component of our cost of sales. Our CODM considers this information injunction with test report deliveries in assessing budgeted and actual operational performance and in allocating resources. Clinical Studies and Publication Costs Clinical studies and publication costs include expenses incurred through our pipeline initiatives as well as in gathering evidence to support the clinical validity and utility of our existing test portfolio. Our CODM considers this information in their assessment of R&D results and in planning and budgeting activities. Professional Services Professional services include expenses incurred for legal and advisory services across our business as well as expenses incurred for services provided by our independent auditors. Professional service expenses are a component of cost of sales, R&D expense and SG&A expense. Our CODM considers this information in their assessment of operating expense results and in planning and budgeting activities. F-39 Table of Contents CASTLE BIOSCIENCES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued) Other Segment Items Other segment items include all other operating expenses types to included IT service and software licensing costs, fixed and variable expenses incurred for leasing of facilities and equipment, depreciation and amortization, gain or losses on disposal of fixed assets in the routine course of business, fair value adjustment for equity securities, realized gains or losses on investment securities, foreign currency exchange for certain equity securities and loan receivable, administrative costs, expense for use of prepaids to include insurance premiums and warranties for lab equipment, public company costs (less audit fees), interest and other non-operating income and income tax expense or benefits. Our CODM does not individually review budgets or results for these activities. Other amounts included in the measure of segment loss or profit were as follows (in thousands): Years Ended December 31, 2025 2024 2023 Interest income $ 11,772 $ 12,916 $ 10,623 Interest expense $ 86 $ 577 $ 11 Depreciation and amortization $ 40,771 $ 15,997 $ 12,330 Income tax (benefit) expense $ ( 5,356 ) $ 3,319 $ 101 Stock-based compensation expense $ 45,893 $ 50,320 $ 51,219 Net gains on equity securities $ 1,466 $ 555 $ — Total assets for our reportable segment were located in the U.S. and were $ 578.6 million and $ 531.2 million as of December 31, 2025 and 2024, respectively. Expenditures for additions to long-lived assets were $ 45.1 million, $ 29.3 million and $ 13.5 million for the years ended December 31, 2025, 2024 and 2023, respectively. 17. Subsequent Events On January 26, 2026, in connection with SciBase’s rights offering, we completed an amendment to our previously disclosed subscription commitment. We agreed to increase our commitment to subscribe for shares without subscription rights from 115.0 million shares to 125.0 million shares. This amendment was intended to achieve an outcome substantially similar to full participation under our subscription rights. In addition, we purchased subscription rights for another 30.5 million shares from a separate SciBase shareholder. These purchased rights, together with our shares without subscription rights, aggregated to a total share purchase of 155.5 million shares for $ 3.6 million. F-40