Amphastar Pharmaceuticals, Inc. 10-K

Item 8. Financial Statements and Supplementary Data. Index to Amphastar Pharmaceuticals, Inc. Consolidated Financial Statements ​ ​ ​ ​ Report of Independent Registered Public Accounting Firm (PCAOB ID: 42 ) ​ ​ ​ 101 Consolidated Balance Sheets ​ 103 ​ Consolidated Statements of Operations ​ 104 ​ Consolidated Statements of Comprehensive Income ​ 105 ​ Consolidated Statements of Stockholders’ Equity ​ 106 ​ Consolidated Statements of Cash Flows ​ 107 ​ Notes to Consolidated Financial Statements ​ 108 ​ ​ ​ ​ 100 Table of Contents Report of Independent Registered Public Accounting Firm To the Stockholders and the Board of Directors of Amphastar Pharmaceuticals, Inc. Opinion on the Financial Statements We have audited the accompanying consolidated balance sheets of Amphastar Pharmaceuticals, Inc. (the Company) as of December 31, 2025 and 2024, the related consolidated statements of operations, comprehensive income, stockholders' equity and cash flows for each of the three years in the period ended December 31, 2025, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025, in conformity with U.S. generally accepted accounting principles. ​ We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company's internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control—Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (2013 framework), and our report dated February 26, 2026 expressed an unqualified opinion thereon. Basis for Opinion These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the 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 audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. Our audits included performing procedures to assess the risks of material misstatement of the 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 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 financial statements. We believe that our audits provide a reasonable basis for our opinion. Critical Audit Matter ​ The critical audit matter communicated below is a matter arising from the current period audit of the 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 financial statements and (2) involved our especially challenging, subjective or complex judgments. The communication of the 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. Reserves for chargebacks and rebates Description of the Matter The Company’s reserves for chargebacks and rebates totaled $79.2 million at December 31, 2025. As described in Note 3 to the consolidated financial statements, the Company estimates chargebacks and rebates using the expected value method at the time of sale to customers based on inventory stocking levels, historical chargeback and rebate rates, and current contract pricing. Auditing the estimates for chargebacks and rebates was complex due to the judgmental nature of the assumptions used. In particular, for product that remains in the distribution channel at December 31, 2025, management is required to estimate the applicable rates that are utilized to calculate the ending chargebacks and rebate reserves. 101 Table of Contents How We Addressed the Matter in Our Audit We obtained an understanding, evaluated the design and tested the operating effectiveness of internal controls over the chargebacks reserve estimation process. This included testing controls over management’s review of significant assumptions and inputs used for the chargebacks reserve estimate, including actual sales, historical experience, wholesaler inventory levels, and contract pricing. To test the reserve for chargebacks, we evaluated the reasonableness of the applicable chargebacks rate by comparing rates at different time periods, including historical and subsequent periods, and performing sensitivity analyses over those rates. We evaluated subsequent activity to assess whether there was any new information that would require adjustment to the reserve. To test the reserve for rebates, we assessed the reasonableness of management’s rebate rates assumptions by evaluating the historical trends, developing an independent range of the assumptions, and testing a sample of rebate payments. We also evaluated subsequent activity to assess whether there was any new information that would require adjustment to the reserve. ​ /s/ Ernst & Young LLP We have served as the Company’s auditor since 1998. Irvine, California February 26, 2026 ​ ​ 102 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. CONSOLIDATED BALANCE SHEETS (in thousands, except share data) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ December 31, ​ ​ 2025 ​ 2024 ASSETS ​ ​ ​ ​ ​ ​ Current assets: ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 170,177 ​ $ 151,609 Restricted cash ​ ​ 235 ​ ​ 235 Short-term investments ​ ​ 112,635 ​ ​ 70,036 Restricted short-term investments ​ 2,200 ​ 2,200 Accounts receivable, net ​ 143,560 ​ 136,289 Inventories ​ 176,890 ​ 153,741 Income tax refunds and deposits ​ 17,167 ​ 1,747 Prepaid expenses and other assets ​ 13,152 ​ 18,214 Total current assets ​ 636,016 ​ 534,071 ​ ​ ​ ​ ​ ​ ​ Property, plant, and equipment, net ​ 310,567 ​ 297,345 Finance lease right-of-use assets ​ ​ 221 ​ ​ 383 Operating lease right-of-use assets ​ ​ 42,931 ​ ​ 46,899 Goodwill and intangible assets, net ​ 565,965 ​ 590,660 Long-term investments ​ ​ — ​ ​ 10,996 Other assets ​ 31,135 ​ 25,992 Deferred tax assets ​ 42,464 ​ 71,124 Total assets ​ $ 1,629,299 ​ $ 1,577,470 ​ ​ ​ ​ ​ ​ ​ LIABILITIES AND STOCKHOLDERS' EQUITY ​ ​ ​ ​ ​ ​ Current liabilities: ​ ​ ​ ​ ​ ​ Accounts payable and accrued liabilities ​ $ 148,348 ​ $ 157,057 Income taxes payable ​ 239 ​ 9,664 Current portion of long-term debt ​ 1,641 ​ 234 Current portion of operating lease liabilities ​ ​ 7,928 ​ ​ 6,804 Total current liabilities ​ 158,156 ​ 173,759 ​ ​ ​ ​ ​ ​ ​ Long-term reserve for income tax liabilities ​ 5,926 ​ 6,957 Long-term debt, net of current portion and unamortized debt issuance costs ​ 608,749 ​ 601,630 Long-term operating lease liabilities, net of current portion ​ ​ 37,684 ​ ​ 41,881 Other long-term liabilities ​ 29,979 ​ 20,945 Total liabilities ​ 840,494 ​ 845,172 Commitments and contingencies (see Note 17) ​ ​ ​ ​ ​ ​ Stockholders’ equity: ​ ​ ​ ​ ​ ​ Preferred stock: par value $ 0.0001 ; 20,000,000 shares authorized; no shares issued and outstanding ​ — ​ — Common stock: par value $ 0.0001 ; 300,000,000 shares authorized; 61,779,883 and 45,645,497 shares issued and outstanding, respectively, as of December 31, 2025 and 60,847,124 and 47,617,691 shares issued and outstanding, respectively, as of December 31, 2024 ​ 6 ​ 6 Additional paid-in capital ​ 535,380 ​ 505,400 Retained earnings ​ 666,881 ​ 568,787 Accumulated other comprehensive loss ​ ( 5,314 ) ​ ( 9,181 ) Treasury stock ​ ( 408,148 ) ​ ( 332,714 ) Total stockholders' equity ​ ​ 788,805 ​ ​ 732,298 Total liabilities and stockholders’ equity ​ $ 1,629,299 ​ $ 1,577,470 See accompanying notes to consolidated financial statements. ​ 103 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. CONSOLIDATED STATEMENTS OF OPERATIONS (in thousands, except per share data) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2025 ​ ​ ​ 2024 ​ ​ ​ 2023 Net revenues: ​ ​ ​ ​ ​ ​ ​ ​ ​ Product revenues, net ​ $ 719,887 ​ $ 712,814 ​ $ 593,238 Other revenues ​ ​ — ​ ​ 19,153 ​ ​ 51,157 Total net revenues ​ ​ 719,887 ​ ​ 731,967 ​ ​ 644,395 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cost of revenues ​ 363,830 ​ 358,112 ​ 293,274 Gross profit ​ 356,057 ​ 373,855 ​ 351,121 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating expenses: ​ ​ ​ ​ ​ ​ ​ ​ ​ Selling, distribution, and marketing ​ 43,885 ​ 37,802 ​ 28,853 General and administrative ​ 85,925 ​ 56,720 ​ 51,540 Research and development ​ 85,844 ​ 73,914 ​ 73,741 Total operating expenses ​ 215,654 ​ 168,436 ​ 154,134 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income from operations ​ 140,403 ​ 205,419 ​ 196,987 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-operating expenses: ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest income ​ 8,679 ​ 10,612 ​ 5,459 Interest expense ​ ( 25,481 ) ​ ( 30,343 ) ​ ( 27,158 ) Other income (expenses), net ​ 23 ​ 4,076 ​ ( 3,929 ) Total non-operating expenses, net ​ ( 16,779 ) ​ ( 15,655 ) ​ ( 25,628 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income before income taxes ​ 123,624 ​ 189,764 ​ 171,359 Income tax provision ​ 25,530 ​ 29,672 ​ 31,833 Income before equity in losses of unconsolidated affiliate ​ ​ 98,094 ​ ​ 160,092 ​ ​ 139,526 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equity in losses of unconsolidated affiliate ​ ​ — ​ ​ ( 573 ) ​ ​ ( 1,981 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ​ $ 98,094 ​ $ 159,519 ​ $ 137,545 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ $ 2.10 ​ $ 3.29 ​ $ 2.85 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted ​ $ 2.03 ​ $ 3.06 ​ $ 2.60 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares used to compute net income per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ 46,743 ​ 48,429 ​ 48,265 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted ​ 48,215 ​ 52,058 ​ 53,001 See accompanying notes to consolidated financial statements. ​ 104 Table of Contents ​ AMPHASTAR PHARMACEUTICALS, INC. CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2025 ​ ​ ​ 2024 ​ ​ ​ 2023 Net income ​ $ 98,094 ​ $ 159,519 ​ $ 137,545 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other comprehensive income (loss), net of income taxes ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign currency translation adjustment ​ 3,867 ​ ( 695 ) ​ 298 Change in pension obligations ​ — ​ ​ ( 8 ) ​ ​ ( 152 ) Total other comprehensive income (loss) ​ 3,867 ​ ( 703 ) ​ 146 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total comprehensive income ​ $ 101,961 ​ $ 158,816 ​ $ 137,691 ​ See accompanying notes to consolidated financial statements. ​ ​ 105 Table of Contents Amphastar Pharmaceuticals, Inc. Consolidated Statements of Stockholders’ Equity (in thousands, except share data) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Common Stock ​ ​ ​ ​ ​ ​ ​ Accumulated ​ Treasury Stock ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Additional ​ ​ ​ ​ Other ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Paid-in ​ Retained ​ Comprehensive ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares ​ Amount ​ Capital ​ Earnings ​ loss ​ Shares ​ Amount ​ Total Balance as of December 31, 2022 58,110,231 ​ $ 6 ​ $ 455,077 ​ $ 271,723 ​ $ ( 8,624 ) ( 9,998,162 ) ​ $ ( 189,524 ) ​ $ 528,658 ​ Net income — ​ — ​ — ​ 137,545 ​ — — ​ — ​ 137,545 ​ Other comprehensive income — ​ — ​ — ​ — ​ 146 — ​ — ​ 146 ​ Purchase of treasury stock — ​ — ​ — ​ — ​ — ( 1,338,757 ) ​ ​ ( 58,144 ) ​ ( 58,144 ) ​ Issuance of treasury stock in connection with the Company's equity plans ​ — ​ — ​ ( 237 ) ​ — ​ — 15,606 ​ ​ 237 ​ — ​ Issuance of common stock in connection with the Company's equity plans 1,279,963 ​ — ​ 10,974 ​ — ​ — — ​ — ​ 10,974 ​ Share-based compensation expense — ​ — ​ 20,242 ​ — ​ — — ​ — ​ 20,242 ​ Balance as of December 31, 2023 59,390,194 ​ $ 6 ​ $ 486,056 ​ $ 409,268 ​ $ ( 8,478 ) ( 11,321,313 ) ​ $ ( 247,431 ) ​ $ 639,421 ​ Net income — ​ — ​ — ​ 159,519 ​ — — ​ — ​ 159,519 ​ Other comprehensive loss — ​ — ​ — ​ — ​ ( 703 ) — ​ — ​ ( 703 ) ​ Purchase of treasury stock — ​ — ​ — ​ — ​ — ( 1,919,670 ) ​ ​ ( 85,458 ) ​ ( 85,458 ) ​ Issuance of treasury stock in connection with the Company's equity plans ​ — ​ — ​ ( 175 ) ​ — ​ — 11,550 ​ ​ 175 ​ — ​ Issuance of common stock in connection with the Company's equity plans 1,456,930 ​ — ​ ( 4,849 ) ​ — ​ — — ​ — ​ ( 4,849 ) ​ Share-based compensation expense — ​ — ​ 24,368 ​ — ​ — — ​ — ​ 24,368 ​ Balance as of December 31, 2024 60,847,124 ​ $ 6 ​ $ 505,400 ​ $ 568,787 ​ $ ( 9,181 ) ( 13,229,433 ) ​ $ ( 332,714 ) ​ $ 732,298 ​ Net income — ​ — ​ — ​ 98,094 ​ — — ​ — ​ 98,094 ​ Other comprehensive income — ​ — ​ — ​ — ​ 3,867 — ​ — ​ 3,867 ​ Purchase of treasury stock — ​ — ​ — ​ — ​ — ( 2,915,580 ) ​ ​ ( 75,586 ) ​ ( 75,586 ) ​ Issuance of treasury stock in connection with the Company's equity plans ​ — ​ — ​ ( 152 ) ​ — ​ — 10,627 ​ ​ 152 ​ — ​ Issuance of common stock in connection with the Company's equity plans 932,759 ​ — ​ 2,855 ​ — ​ — — ​ — ​ 2,855 ​ Share-based compensation expense — ​ — ​ 27,277 ​ — ​ — — ​ — ​ 27,277 ​ Balance as of December 31, 2025 61,779,883 ​ $ 6 ​ $ 535,380 ​ $ 666,881 ​ $ ( 5,314 ) ( 16,134,386 ) ​ $ ( 408,148 ) ​ $ 788,805 ​ See accompanying notes to consolidated financial statements. ​ ​ 106 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. CONSOLIDATED STATEMENTS OF CASH FLOWS (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2025 ​ ​ ​ 2024 ​ ​ ​ 2023 Cash Flows From Operating Activities: ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ​ $ 98,094 ​ $ 159,519 ​ $ 137,545 Reconciliation to net cash provided by operating activities: ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss on disposal of assets ​ 39 ​ ​ 9 ​ ​ 475 Impairment of long-lived assets ​ ​ — ​ ​ — ​ ​ 2,700 Loss (gain) on interest rate swaps and foreign currency transactions, net ​ ​ 2,492 ​ ​ ( 2,792 ) ​ ​ 5,330 Depreciation of property, plant, and equipment ​ 31,647 ​ ​ 28,249 ​ ​ 25,205 Amortization of intangible assets ​ 25,048 ​ ​ 24,718 ​ ​ 12,830 Operating lease right-of-use asset amortization ​ ​ 6,506 ​ ​ 4,238 ​ ​ 3,742 Amortization of discounts, premiums, and debt issuance costs ​ ​ 3,355 ​ ​ 6,032 ​ ​ 11,399 Equity in losses of unconsolidated affiliate ​ ​ — ​ ​ 573 ​ ​ 1,981 Share-based compensation expense ​ 27,277 ​ ​ 24,368 ​ ​ 20,242 Changes in reserve for uncertain tax positions ​ ( 1,032 ) ​ ​ 891 ​ ​ ( 1,159 ) Changes in deferred taxes, net ​ 28,660 ​ ​ ( 17,872 ) ​ ​ ( 12,578 ) Changes in operating assets and liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts receivable, net ​ ( 6,367 ) ​ ​ ( 21,671 ) ​ ​ ( 26,086 ) Inventories ​ ( 21,063 ) ​ ​ ( 48,797 ) ​ ​ ( 1,724 ) Prepaid expenses and other assets ​ ( 3,530 ) ​ ​ ( 10,726 ) ​ ​ ( 2,728 ) Income tax refunds, deposits, and payable, net ​ ( 24,843 ) ​ ​ 6,834 ​ ​ ( 3,319 ) Operating lease liabilities ​ ​ ( 5,609 ) ​ ​ ( 3,750 ) ​ ​ ( 3,589 ) Accounts payable and accrued liabilities ​ ( 4,559 ) ​ ​ 63,563 ​ ​ 13,237 Net cash provided by operating activities ​ 156,115 ​ 213,386 ​ 183,503 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash Flows From Investing Activities: ​ ​ ​ ​ ​ ​ ​ ​ ​ BAQSIMI ® acquisition ​ — ​ ( 129,000 ) ​ ( 506,406 ) Purchases and construction of property, plant, and equipment ​ ( 34,882 ) ​ ( 41,041 ) ​ ( 38,166 ) Purchase of intangible assets ​ ​ ( 2,250 ) ​ ​ — ​ ​ — Purchase of investments ​ ​ ( 119,130 ) ​ ​ ( 76,792 ) ​ ​ ( 144,556 ) Maturity of investments ​ ​ 90,291 ​ ​ 126,022 ​ ​ 38,622 Deposits and other assets ​ ( 4,361 ) ​ ( 4,119 ) ​ 1,390 Net cash used in investing activities ​ ( 70,332 ) ​ ( 124,930 ) ​ ( 649,116 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash Flows From Financing Activities: ​ ​ ​ ​ ​ ​ ​ ​ ​ Proceeds from equity plans, net of withholding tax payments ​ 2,855 ​ ( 4,849 ) ​ 10,974 Purchase of treasury stock ​ ( 75,586 ) ​ ( 85,458 ) ​ ( 58,144 ) Debt issuance costs ​ ​ ( 687 ) ​ ​ ( 816 ) ​ ​ ( 25,079 ) Proceeds from borrowing under lines of credit ​ 6,216 ​ 18,433 ​ — Proceeds from issuance of long-term debt ​ — ​ — ​ 845,000 Principal payments on long-term debt ​ ( 223 ) ​ ( 8,263 ) ​ ( 318,658 ) Net cash provided by (used in) financing activities ​ ( 67,425 ) ​ ( 80,953 ) ​ 454,093 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Effect of exchange rate changes on cash ​ 210 ​ ( 190 ) ​ ( 282 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net increase (decrease) in cash, cash equivalents, and restricted cash ​ 18,568 ​ 7,313 ​ ( 11,802 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash, cash equivalents, and restricted cash at beginning of period ​ 151,844 ​ 144,531 ​ 156,333 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash, cash equivalents, and restricted cash at end of period ​ $ 170,412 ​ $ 151,844 ​ $ 144,531 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Noncash Investing and Financing Activities: ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred payment for BAQSIMI ® acquisition ​ $ — ​ $ — ​ $ 121,699 Capital expenditures included in accounts payable ​ $ 7,741 ​ $ 5,622 ​ $ 4,454 Operating lease right-of-use assets in exchange for operating lease liabilities ​ $ 2,537 ​ $ 18,804 ​ $ 10,521 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Supplemental Disclosures of Cash Flow Information: ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest paid, net of capitalized interest ​ $ 23,218 ​ $ 26,811 ​ $ 17,573 Income taxes paid ​ $ 22,710 ​ $ 40,104 ​ $ 49,001 See accompanying notes to consolidated financial statements ​ 107 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ Note 1. Business ​ Amphastar Pharmaceuticals, Inc., a Delaware corporation (together with its subsidiaries, hereinafter referred to as the “Company”), is a biopharmaceutical company that focuses on developing, manufacturing, and commercializing technically challenging generic and proprietary injectable, inhalation, and intranasal products, including products with high technical barriers to market entry. Additionally, the Company sells active pharmaceutical ingredient, or API, products. Most of the Company’s products are contracted and distributed through group purchasing organizations, drug wholesalers, and drug retailers. The Company’s insulin API products are sold to other pharmaceutical companies for use in their own products and are being used by the Company in the development of injectable pharmaceutical products. ​ Note 2. Summary of Significant Accounting Policies ​ Basis of Presentation ​ The accompanying consolidated financial statements include the accounts of the Company and its subsidiaries, and are prepared in accordance with United States generally accepted accounting principles, or GAAP. All intercompany activity has been eliminated in the preparation of the consolidated financial statements. In the opinion of management, the accompanying consolidated financial statements include all adjustments, which are of a normal recurring nature, necessary to present fairly the consolidated financial position, results of operations, and cash flows of the Company. ​ The Company’s subsidiaries include: (1) International Medication Systems, Limited, or IMS, (2) Armstrong Pharmaceuticals, Inc., or Armstrong, (3) Amphastar Nanjing Pharmaceuticals Inc., or ANP, (4) Amphastar France Pharmaceuticals, S.A.S., or AFP, (5) Amphastar UK Ltd., or AUK, and (6) International Medication Systems (UK) Limited, or IMS UK. ​ Investment in Unconsolidated Affiliate ​ The Company applies the equity method of accounting for investments when it has significant influence, but not controlling interest in the investee. The Company’s proportionate share of the earnings or losses resulting from these investments is reported as “Equity in losses of unconsolidated affiliate” in the accompanying consolidated statements of operations. Investments accounted for using the equity method may be reported on a lag of up to three months if financial statements of the investee are not available in sufficient time for the investor to apply the equity method as of the current reporting date. ​ The Company’s equity method investments are reported at cost and adjusted each period for the Company’s share of the investee’s earnings or losses and dividends paid, if any. ​ Use of Estimates ​ The preparation of the consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. The principal accounting estimates include: fair value of financial instruments, allowance for credit losses, discounts, chargebacks and rebates, product returns, adjustment of inventory to its net realizable value, impairment of investments, long-lived and intangible assets and goodwill, litigation reserves, stock price volatility for share-based compensation expense, valuation allowances for deferred tax assets, and liabilities for uncertain income tax positions. ​ Foreign Currency ​ The functional currency of the Company, its domestic subsidiaries, its Chinese subsidiary ANP, and its U.K. subsidiary, AUK, is the U.S. Dollar, or USD. ANP maintains its books of record in Chinese yuan. These books are remeasured into the functional currency of USD using the current or historical exchange rates. The resulting currency remeasurement 108 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ adjustments and other transactional foreign currency exchange gains and losses are reflected in the Company’s accompanying consolidated statements of operations. ​ The Company’s French subsidiary, AFP, maintains its books of record in euros. AUK’s subsidiary, IMS UK, maintains its books of record in British pounds. These local currencies have been determined to be the subsidiaries’ respective functional currencies. Activities in the statements of operations are translated to USD using average exchange rates during the period. Assets and liabilities are translated at the rate of exchange prevailing on the balance sheet date. Equity is translated at the prevailing rate of exchange at the date of the equity transactions. Translation adjustments are reflected in stockholders’ equity and are included as a component of other comprehensive income. The unrealized gains or losses of intercompany foreign currency transactions that are of a long-term investment nature are reported in other accumulated comprehensive income. ​ The unrealized gains and losses of intercompany foreign currency transactions that are of a long-term investment nature for the years ended December 31, 2025, 2024, and 2023 were a $ 4.0 million gain, a $ 1.9 million loss, and a $ 1.1 million gain, respectively. ​ Comprehensive Income ​ The Company’s comprehensive income includes its foreign currency translation gains and losses and changes in pension obligations. ​ Acquisitions ​ The Company evaluates acquisitions and other similar transactions to assess whether or not the transaction should be accounted for as a business combination or asset acquisition by first applying a screen test to determine if substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or group of similar identifiable assets. If the screen is met, the transaction is accounted for as an asset acquisition. If the screen is not met, further determination is required as to whether or not the Company has acquired inputs and substantive processes that have the ability to create outputs, which would meet the definition of a business. ​ Acquisitions meeting the definition of business combinations are accounted for using the acquisition method of accounting, which requires that the purchase price be allocated to the net assets acquired at their respective fair values. In a business combination, any excess of the purchase price over the estimated fair values of the net assets acquired is recorded as goodwill. ​ For asset acquisitions, a cost accumulation model is used to determine the cost of an asset acquisition. Direct transaction costs are recognized as part of the cost of an asset acquisition. The cost of an asset acquisition, including transaction costs, is allocated to identifiable assets acquired and liabilities assumed based on a relative fair value basis, with the exception of non-qualifying assets. Goodwill is not recognized in an asset acquisition. When a transaction accounted for as an asset acquisition includes an in-process research and development, or IPR&D, asset, the IPR&D asset is only capitalized if it has an alternative future use other than in a particular research and development project. Asset acquisitions may include contingent consideration arrangements that encompass obligations to make future payments to sellers contingent upon the achievement of future financial targets. Contingent consideration, including assumed contingent considerations, is not recognized until all contingencies are resolved and the consideration is paid or becomes payable (unless contingent considerations meets the definition of a derivative, in which case the amount becomes part of the basis in the asset acquired), at which point the consideration is allocated to the assets acquired based on their relative fair values at the acquisition date, with the exception of non-qualifying assets. ​ Judgments are used in determining estimates of useful lives of long-lived assets. Useful life estimates are based on, among other factors, estimates of expected future net cash flows, the assessment of each asset’s life cycle, and the impact of competitive trends on each asset’s life cycle and other factors. These judgments can materially impact the estimates used to allocate purchase consideration to assets acquired and liabilities assumed, and the resulting timing and amounts 109 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ charged to or recognized in current and future operating results. For these and other reasons, actual results may vary significantly from estimated results. ​ Shipping and Handling Costs ​ For the years ended December 31, 2025, 2024, and 2023, the Company included shipping and handling costs of approximately $ 8.1 million, $ 8.0 million and $ 7.0 million, respectively, in selling, distribution and marketing expenses in the accompanying consolidated statements of operations. ​ Advertising Expense ​ Advertising expenses, primarily associated with Primatene MIST ® , are recorded as they are incurred, except for expenses related to the development of a major commercial or media campaign, which are expensed in the period in which the commercial or campaign is first presented, and are reflected as a component of selling, distribution and marketing in the Company’s consolidated statements of operations. For the years ended December 31, 2025, 2024, and 2023, advertising expenses were $ 10.2 million, $ 10.5 million, and $ 10.4 million, respectively. ​ Research and Development Costs ​ Research and development costs are charged to expense as incurred and consist of costs incurred to further the Company’s research and development activities. These include salaries and related employee benefits, costs associated with clinical trials, nonclinical research and development activities, regulatory activities, license fees, milestone payments upon the achievement of clinical, or regulatory events, materials, supplies, research-related overhead expenses and fees paid to external service providers. ​ The Company has entered into, and may continue to enter into, license agreements to access and utilize certain technology. In each case, the Company evaluates if the license agreement results in the acquisition of an asset or a business. To date, none of the Company's license agreements have been considered an acquisition of a business. For asset acquisitions, the upfront payments to acquire such licenses, as well as any future milestone payments made before product approval that do not meet the definition of a derivative, are immediately recognized as research and development expense in the statements of operations when paid or become payable, provided there is no alternative future use of rights in other research and development projects. ​ Financial Instruments ​ The Company’s accompanying consolidated balance sheets include the following financial instruments: cash and cash equivalents, restricted cash, accounts receivable, accounts payable, accrued liabilities, short-term borrowings and long-term obligations. The Company considers the carrying amounts of current assets and liabilities on the consolidated balance sheets to approximate the fair value of these financial instruments due to the short maturity of these items. The carrying value of the Company’s long-term obligations, with the exception of the convertible debt (See Note 13) approximates their fair value, as the stated borrowing rates are comparable to rates currently offered to the Company for instruments with similar maturities. The Company at times enters into interest rate swap contracts to manage its exposure to interest rate changes and its overall cost of long-term debt. The Company’s interest rate swap contracts exchange the variable interest rates for fixed interest rates. ​ Cash and Cash Equivalents ​ Cash and cash equivalents consist of cash, money market accounts, certificates of deposit and highly liquid investments with original maturities of three months or less. ​ ​ 110 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ Investments ​ Investments as of December 31, 2025 and 2024 consisted of certificates of deposit and investment grade corporate, agency, and municipal bonds with original maturity dates between three and thirty-six months. ​ Restricted Cash ​ Restricted cash is collateral required for the Company to guarantee certain vendor payments in France. As of December 31, 2025 and 2024, the restricted cash balance was $ 0.2 million. ​ Restricted Short-Term Investments ​ Restricted short-term investments consist of certificates of deposit that are collateral for standby letters of credit to qualify for workers’ compensation self-insurance. The certificates of deposit have original maturities greater than three months, but less than one year. As of December 31, 2025 and 2024, the balance of restricted short-term investments was $ 2.2 million. ​ Accounts receivable and Allowance for Credit Losses ​ Accounts receivable generally consists of amounts due from the Company’s customers, which primarily includes pharmaceutical wholesalers and drug retailers. Accounts receivable is recorded net of discounts, chargebacks, allowances and other adjustments. The Company evaluates the collectability of accounts receivable based on a combination of factors. When the Company is aware of circumstances that may impair a customer’s ability to pay subsequent to the original sale, the Company records a specific allowance to reduce the amounts receivable to the amount that the Company reasonably believes to be collectable. For all other customers, the Company recognizes an allowance for credit losses based on factors that include the length of time the receivables are past due, industry and geographic concentrations, the current economic conditions and historical collection experience. As of December 31, 2025 and 2024, the Company's allowance for credit losses was $ 3.3 million and $ 3.5 million, respectively. ​ Inventories ​ Inventories consist of currently marketed products. The Company states inventory at the lower of cost or net realizable value. Cost is determined in a manner that approximates the first-in, first-out method. Provisions are made for slow moving, unsellable, or obsolete items. Net realizable value is determined using the estimated selling price, in the ordinary course of business, less estimated costs to complete and dispose. ​ The Company may produce or purchase inventories prior to or with the expectation of receiving regulatory approval in the near term, based on operational decisions about the most effective use of existing resources. This inventory is referred to as pre-launch inventory. It is the Company’s accounting policy that the pre-launch inventory is capitalized if it has a probable future economic benefit at the time it is purchased or manufactured. If regulatory approval is received and previously expensed pre-launch inventory is sold, such sales may contribute up to a 100% margin to the Company’s operating results. Pre-launch inventory costs include cost of work in process, materials, and finished drug products. For the years ended December 31, 2025, 2024, and 2023, the Company did not have material capitalized pre-launch inventory. ​ ​ 111 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ Property, Plant and Equipment Property, plant and equipment are stated at cost or, in the case of assets acquired in a business combination, at fair value on the purchase date. Depreciation and amortization expense is computed using the straight-line method over the estimated useful lives of the related assets as follows: ​ ​ ​ ​ Buildings ​ ​ ​ 20 - 31 years Machinery and equipment 3 - 12 years Furniture and fixtures 3 - 7 years Automobiles 4 - 5 years Leasehold improvements Lesser of remaining lease term or useful life ​ Intangible Assets, net ​ The evaluation of intangible assets includes assessing the amortization period for which the asset is expected to contribute to future cash flows of the Company. Intangible assets with finite lives are amortized primarily on a straight-line basis over the period the asset is expected to contribute directly or indirectly to the future cash flows of the Company as follows: ​ ​ ​ ​ Product rights ​ ​ ​ 10 - 24 years Land-use rights 37 - 50 years Other intangibles 6 - 20 years ​ Impairment of Long-Lived Assets, including Identifiable Definite-Lived Intangible Assets ​ The Company assesses long-term and identifiable definite-lived intangible assets or asset groups for impairment when events or changes in circumstances indicate that the carrying amount of an asset or asset group may not be recoverable. If the sum of the expected future undiscounted cash flows is less than the carrying amount of the asset or asset group, further impairment analysis is performed. An impairment loss is measured as the amount by which the carrying amount of the asset or asset groups exceeds the fair value (assets to be held and used) or fair value less cost to sell (assets to be disposed of). The Company also assesses the useful lives of its assets periodically to determine whether events and circumstances warrant a revision to the remaining useful life. Changes in the useful life are adjusted prospectively by revising the remaining period over which the asset is amortized. ​ Deferred Income Taxes ​ The Company utilizes the liability method of accounting for income taxes, under which deferred taxes are determined based on the temporary differences between the financial statements and the tax basis of assets and liabilities using enacted tax rates. A valuation allowance is recorded when it is more likely than not that the deferred tax assets will not be realized. ​ Debt Issuance Costs ​ Debt issuance costs related to non-revolving debt are recognized as a reduction to the related debt balance in the accompanying consolidated balance sheets and amortized to interest expense over the contractual term of the related debt using the effective interest method. Debt issuance costs associated with revolving debt are capitalized within other long-term assets on the consolidated balance sheets and are amortized to interest expense over the term of the related revolving debt. ​ Convertible Debt ​ The Company accounts for its convertible debt instruments as a single unit of account, a liability, because the Company 112 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ concluded that the conversion features do not require bifurcation as a derivative under Accounting Standards Codification, or ASC, 815-15, Derivatives and Hedging and the Company did not issue its convertible debt instruments at a substantial premium. ​ In accordance with Accounting Standards Update, or ASU, 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40) : Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity , the Company evaluates convertible debt instruments to determine if the conversion feature is freestanding or embedded. If the conversion feature does not require derivative treatment under ASC 815, the instrument is evaluated under ASC 470-20, “ Debt with Conversion and Other Options” for consideration of any beneficial conversion features. If no beneficial conversion features exist that require separate recognition, convertible debt instruments are accounted for as a single liability measured at its amortized cost as long as no other features require separation and recognition as derivatives. ​ Capitalized Software Implementation Costs ​ The Company capitalizes certain software implementation costs incurred under a cloud computing arrangement that is a service contract. Costs incurred during the preliminary project phase or planning and research phase are expensed as incurred. Costs incurred during the application development stage related to the implementation of the hosting arrangement are capitalized and included within other assets on the accompanying consolidated balance sheets. Capitalized implementation costs are amortized on a straight-line basis over the term of the associated hosting arrangement when ready for its intended use. Capitalized implementation costs were $ 6.8 million as of December 31, 2025 and are included in other long-term assets in the Company’s consolidated balance sheet. As of December 31, 2024, the Company did no t have any capitalized implementation costs. For the years ended December 31, 2025 and 2024, the Company did no t record any amortization expense for capitalized implementation costs. ​ Impairment of Indefinite-Lived Intangible Asset and Goodwill ​ The Company assesses indefinite lived intangible asset and goodwill for impairment in the fourth quarter of each year or more frequently if indicators of impairment are present. When the Company chooses to perform a qualitative assessment, it evaluates economic, industry and company-specific factors as an initial step. If the Company determines it is more likely than not that the indefinite-lived intangible asset is impaired or the fair value of a reporting unit is less than its carrying amount, further quantitative impairment testing is then performed; otherwise, no further testing is required. An impairment loss is recorded if the asset’s fair value is less than its carrying value. The Company also periodically assesses its indefinite-lived intangible asset to determine if events and circumstances continue to support an indefinite useful life. If the life is no longer indefinite, the asset is tested for impairment. The carrying value, after recognition of any impairment loss, is amortized over its remaining useful life. ​ Self-Insured Claims ​ The Company is self-insured, up to certain limits, for workers’ compensation claims. The Company has purchased stop-loss insurance, which will reimburse the Company for individual claims in excess of $ 350,000 or aggregate minimum attachment of $ 5.4 million annually. The cost of claims reported and an estimate of claims incurred but not reported are charged to operating expenses. A liability for unpaid claims and the associated claim expenses, including incurred but not reported losses, is actuarially determined and reflected in accrued liabilities in the accompanying consolidated balance sheets. Total expense under the program was approximately $ 2.7 million, $ 2.0 million, and $ 1.7 million, for the years ended December 31, 2025, 2024, and 2023, respectively. The self-insured claims liability was $ 6.4 million and $ 5.2 million at December 31, 2025 and 2024, respectively. The determination of such claims and expenses and the appropriateness of the related liability is reviewed periodically and updated, as necessary. Changes in estimates are recorded in the period identified. ​ ​ 113 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ Litigation, Commitments and Contingencies ​ Litigation, commitments and contingencies are accrued when management, after considering the facts and circumstances of each matter as then known, has determined it is probable a liability will be found to have been incurred and the amount of the loss can be reasonably estimated. When only a range of amounts is reasonably estimable and no amount within the range is more likely than another, the low end of the range is recorded. Legal fees are expensed as incurred. Due to the inherent uncertainties surrounding gain contingencies, the Company generally does not recognize potential gains until they are realized. ​ Recent Accounting Pronouncements ​ In December 2023, the Financial Accounting Standard Board, or FASB, issued ASU 2023-09, Income taxes (Topic 740): Improvements to Income Tax Disclosures, which requires entities, on an annual basis, to provide disclosure of specific categories in the rate reconciliation table, as well as disclosure of income taxes paid disaggregated by jurisdiction. The disclosure requirements will be applied prospectively. The Company adopted this guidance on December 31, 2025 and updated its disclosures to conform to this tax disclosure requirements. The adoption of this guidance did not have a material impact on the Company’s consolidated financial statements and related disclosures. ​ In November 2024, the FASB issued ASU 2024-03, Income Statement Reporting-Comprehensive Income-Expense Disaggregation Disclosures (Subtopic 220-40), Disaggregation of Income Statement Expenses. The standard update improves the disclosures about a public business entity’s expenses by requiring more detailed information about the types of expenses (including purchases of inventory, employee compensation, depreciation and amortization) included within income statement expense captions. The guidance will be effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The standard updates are to be applied prospectively with the option for retrospective application. The Company is currently evaluating the impact of disclosure requirements related to the new standard on the Company’s consolidated financial statements and related disclosures. ​ In November 2024, the FASB issued ASU 2024-04, Debt– Debt with Conversion and Other Options, (subtopic 470-20). The update is intended to improve the relevance and consistency in application of the induced conversion guidance in Subtopic 470-20 for (a) convertible debt instruments with cash conversion features and (b) debt instruments that are not currently convertible. ASU 2024-04 is effective for annual reporting periods beginning after December 15, 2025. The Company is currently evaluating the impact of the new standard on the Company’s consolidated financial statements and related disclosures. ​ In September 2025, the FASB issued ASU 2025-06, Intangibles - Goodwill and Other-Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software. The ASU amends the existing standard to remove all references to prescriptive and sequential software development project stages. Under this guidance, eligible software development costs will begin to be capitalized when management has authorized and committed to funding the software project, and it is probable that the project will be completed and the software will be used to perform the function intended. In evaluating whether it is probable the project will be completed; management is required to consider whether there is significant uncertainty associated with the development activities of the software. This guidance is effective for all annual periods beginning after December 15, 2027, and for interim periods within those annual reporting periods, with early adoption permitted. The guidance may be applied on a prospective basis, a modified basis for in-process projects, or a retrospective basis. The Company is currently evaluating the impact of the new standard on the Company’s consolidated financial statements and related disclosures. ​ ​ 114 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ ​ Note 3. Revenue Recognition ​ Product revenues, net ​ In accordance with ASC 606 Revenue from Contracts with Customers , revenue is recognized at the time that the Company’s customers obtain control of the promised goods and we satisfy the Company’s performance obligations, which is generally at the time of product delivery to the Company’s customers. In some cases, the Company’s performance obligation is satisfied and revenue is recognized at the time of shipment when stipulated by the terms of the sale agreements. ​ The consideration to which the Company expects to be entitled includes a stated list price, less various forms of variable consideration including chargebacks and rebates, product returns, prompt pay discounts, distributor fees, patient co-pay assistance, and other related deductions. These deductions to product sales are referred to as gross-to-net deductions and are estimated and recorded in the period in which the related product sales occur. Payment terms offered to customers generally range from 30 to 75 days ; however, payment terms differ by jurisdiction, by customer and, in some instances, by type of product. Revenues from product sales, net of gross-to-net deductions, are recorded only to the extent a significant reversal in the amount of cumulative revenue recognized is not probable of occurring when the uncertainty associated with gross-to-net deductions is subsequently resolved. Taxes assessed by governmental authorities and collected from customers are excluded from product sales. If the Company expects, at contract inception, that the period between the transfer of control and corresponding payment from the customer will be one year or less, the amount of consideration is not adjusted for the effects of a financing component. Shipping and handling activities are considered to be fulfillment activities rather than a separate performance obligation and are recorded within selling, distribution and marketing expenses in the accompanying consolidated statements of operations. ​ Chargebacks and Rebates: Wholesaler chargebacks relate to sales terms under which the Company agrees to reimburse wholesalers for differences between the gross sales prices at which the Company sells its products to wholesalers and the actual prices of such products that wholesalers resell under the Company’s various contractual arrangements with third parties such as hospitals, group purchasing organizations and pharmacy benefit managers in the United States. Rebates include primarily amounts paid to retailers, payers, and providers in the United States, including those paid to Medicare and state Medicaid programs, and are based on contractual arrangements or statutory requirements. The Company estimates chargebacks and rebates using the expected value method at the time of sale to customers based on inventory stocking levels, historical chargeback and rebate rates, and current contract pricing. ​ Chargebacks and rebates are reflected as a component of product revenues, net. The following table is an analysis of the chargeback and rebate activities and ending balances: ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2025 ​ 2024 ​ (in thousands) Beginning balance ​ $ 60,331 ​ ​ ​ $ 27,920 Provision for chargebacks and rebates ​ 445,183 ​ 289,332 Credits and payments issued to third parties ​ ( 426,332 ) ​ ( 256,921 ) Ending balance ​ $ 79,182 ​ $ 60,331 ​ Changes in the chargeback provision from period to period are primarily dependent on the Company’s sales to its wholesalers, the level of inventory held by wholesalers, and the wholesalers’ customer mix. Changes in the rebate provision from period to period are primarily dependent on retailers’ and other indirect customers’ purchases. The approach that the Company uses to estimate chargebacks and rebates has been consistently applied for all periods presented. Variations in estimates have been historically small. The Company continually monitors chargebacks and rebates and makes adjustments when it believes that the actual chargebacks and rebates may differ from the estimates. Accounts receivable and/or accounts payable and accrued liabilities are reduced and/or increased by the chargebacks and rebate amounts depending on whether the Company has the right to offset with the customer. 115 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ Chargebacks and rebates are included in the following balance sheet accounts: ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2025 ​ 2024 ​ (in thousands) Reduction to accounts receivable, net $ 43,820 ​ ​ ​ $ 26,258 Accounts payable and accrued liabilities 35,362 ​ 34,073 Total $ 79,182 ​ $ 60,331 ​ Accrual for Product Returns: The Company offers certain customers the right to return qualified excess or expired inventory for full or partial credit. The Company’s product returns primarily consist of the returns of expired products from sales made in prior periods. Returned products cannot be resold. At the time product revenue is recognized, the Company records an accrual for product returns estimated using the expected value method. The accrual is based, in part, upon the historical relationship of product returns to sales and customer contract terms. The Company also assesses other factors that could affect product returns including market conditions, product obsolescence, and new competition. ​ The provision for product returns is reflected as a component of net revenues. The following table is an analysis of the product return liability: ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2025 ​ 2024 ​ (in thousands) Beginning balance ​ $ 19,859 ​ ​ ​ $ 17,179 Provision for product returns ​ 19,963 ​ 9,597 Credits issued to third parties ​ ( 15,746 ) ​ ( 6,917 ) Ending balance ​ $ 24,076 ​ $ 19,859 ​ The provision for product returns is included in the following balance sheet accounts: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2025 ​ 2024 ​ (in thousands) Accounts payable and accrued liabilities ​ $ 18,568 ​ ​ ​ $ 14,559 Other long-term liabilities ​ 5,508 ​ 5,300 Total ​ $ 24,076 ​ $ 19,859 ​ Prompt Pay Discounts: The Company provides its customers with a percentage discount on their invoice if the customers pay within the agreed upon timeframe. The Company generally expects that its customers will earn such prompt pay discounts. The Company estimates the probability of customers paying promptly based on the percentage of discount outlined in the purchase agreement between the two parties, and deducts the full amount of these discounts from gross product sales and accounts receivable at the time revenue is recognized. ​ Distributor Fees: The Company engages with wholesalers to distribute its products to end customers. The Company pays the wholesalers a fee for services such as: inventory management, chargeback administration, and service level commitments. The Company estimates the amount of distribution services fees to be paid and adjusts the transaction price with the amount of such estimate at the time of sale to the customer. An accrued liability is recorded for unpaid distribution service fees. ​ Patient Co-Pay Assistance: Co-pay assistance represents financial assistance to qualified patients, assisting them with prescription drug co-payments required by insurance. The accrued liability for co-pay is based on an estimate of claims and the cost per claim that the Company expects to receive associated with inventory that exists in the distribution channel at period end. ​ 116 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ Revenues derived from contract manufacturing services are recognized when third-party products are shipped to customers. The Company’s accounting policy is to review each agreement involving contract development and manufacturing services to determine if there are multiple revenue-generating activities that constitute more than one unit of account. Revenues are recognized for each unit of account based on revenue recognition criteria relevant to that unit. ​ Service revenues derived from research and development contracts are recognized over time based on progress toward satisfaction of the performance obligation. For each performance obligation satisfied over time, the Company assesses the proper method to be used for revenue recognition, either an input method to measure progress toward the satisfaction of services or an output method of determining the progress of completion of performance obligation. Revenue from research and development services at ANP was $ 3.2 million, $ 4.2 million, and $ 4.5 million for the years ended December 31, 2025, 2024, and 2023, respectively. ​ Other revenues ​ Revenues related to BAQSIMI ® sales made by Lilly under the TSA during the years ended December 31, 2024, and 2023, were recorded on a net basis, similar to a royalty arrangement. ​ Note 4. Net Income per Share ​ Basic net income per share is calculated based upon the weighted-average number of shares outstanding during the period. Diluted net income per share gives effect to all potentially dilutive shares outstanding during the period, such as stock options, non-vested restricted stock units, and shares issuable under the Company’s Employee Stock Purchase Plan, or ESPP, and potential shares of common stock issuable upon conversion of Convertible Notes of the Company, due March 2029, or the 2029 Convertible Notes. ​ For the year ended December 31, 2025, options to purchase 3,200,705 shares of stock with a weighted-average exercise price of $ 35.00 per share were excluded in the computation of diluted net income per share because their effect would be anti-dilutive. The 2029 Convertible Notes had no impact on the computation of diluted net income per share as the average stock price during the period was less than the conversion price. ​ For the year ended December 31, 2024, options to purchase 618,973 shares of stock with a weighted-average exercise price of $ 46.63 per share were excluded in the computation of diluted net income per share because their effect would be anti-dilutive. The 2029 Convertible Notes had no impact on the computation of diluted net income per share as the average stock price during the period was less than the conversion price. ​ For the year ended December 31, 2023, the Company did no t have any options that were excluded in the computation of diluted net income per share because the effect would be anti-dilutive. The 2029 Convertible Notes had no impact on the computation of diluted net income per share as the average stock price during the period was less than the conversion price. ​ 117 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ The following table provides the calculation of basic and diluted net income per share for each of the periods presented: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2025 ​ 2024 ​ 2023 ​ ​ (in thousands, except per share data) Basic and dilutive numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ​ $ 98,094 ​ $ 159,519 ​ $ 137,545 Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares outstanding — basic ​ 46,743 ​ 48,429 ​ 48,265 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net effect of dilutive securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ Incremental shares from equity awards ​ 1,472 ​ 3,629 ​ 4,736 Weighted-average shares outstanding — diluted ​ 48,215 ​ 52,058 ​ 53,001 Net income per share — basic ​ $ 2.10 ​ $ 3.29 ​ $ 2.85 Net income per share — diluted ​ $ 2.03 ​ $ 3.06 ​ $ 2.60 ​ ​ Note 5. Segment Reporting ​ The Company’s business is the development, manufacture, and marketing of pharmaceutical products (see Note 1). The Company’s Chief Executive Officer, is the Chief Operating Decision Maker, or CODM. ​ The CODM uses consolidated information to assess the Company’s performance. As a result, the Company has one reportable segment, pharmaceutical products. ​ The measure of segment assets is reported on the consolidated balance sheets as total assets. ​ Selected segment financial information is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2025 ​ 2024 ​ 2023 ​ ​ (in thousands) Net revenues: ​ $ 719,887 ​ $ 731,967 ​ $ 644,395 Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ Payroll expense ​ ​ 191,787 ​ ​ 191,274 ​ ​ 173,818 Materials and supplies ​ ​ 43,314 ​ ​ 46,111 ​ ​ 46,134 Clinical trials expense ​ ​ 3,038 ​ ​ 594 ​ ​ 5,216 Depreciation and amortization expense ​ ​ 56,695 ​ ​ 52,967 ​ ​ 38,035 Stock-based compensation expense ​ ​ 27,277 ​ ​ 24,368 ​ ​ 20,242 Consulting and outside services expense ​ ​ 39,771 ​ ​ 27,772 ​ ​ 17,698 Advertising and promotional expense ​ ​ 13,138 ​ ​ 11,559 ​ ​ 11,123 Other segment items (1) ​ ​ 204,441 ​ ​ 167,827 ​ ​ 139,071 Interest income ​ ​ ( 8,679 ) ​ ​ ( 10,612 ) ​ ​ ( 5,459 ) Interest expense ​ ​ 25,481 ​ ​ 30,343 ​ ​ 27,158 Income tax provision ​ ​ 25,530 ​ ​ 29,672 ​ ​ 31,833 Equity in losses of unconsolidated affiliate ​ ​ — ​ ​ 573 ​ ​ 1,981 Net income ​ $ 98,094 ​ $ 159,519 ​ $ 137,545 (1) Other segment items primarily include maintenance and repairs expense, travel expense, professional services expense, legal expense, rent expense, product costs, certain overhead expenses, manufacturing cost absorption and variances, inventory provisions, miscellaneous expenses, and foreign currency exchange gains and losses . ​ ​ 118 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ Net revenues by product are presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2025 ​ 2024 ​ 2023 ​ ​ (in thousands) Product revenues, net: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ BAQSIMI ® ​ $ 185,358 ​ $ 126,898 ​ $ — Primatene MIST ® ​ ​ 108,669 ​ ​ 102,012 ​ ​ 89,321 Epinephrine ​ ​ 70,643 ​ ​ 94,090 ​ ​ 81,650 Glucagon ​ ​ 69,084 ​ ​ 108,319 ​ ​ 113,684 Lidocaine ​ ​ 56,479 ​ ​ 55,854 ​ ​ 58,162 Other products ​ 229,654 ​ 225,641 ​ 250,421 Total product revenues, net ​ ​ 719,887 ​ ​ 712,814 ​ ​ 593,238 Other revenues ​ ​ — ​ ​ 19,153 ​ ​ 51,157 Total net revenues ​ $ 719,887 ​ $ 731,967 ​ $ 644,395 ​ Net revenues and carrying values of long-lived assets, which includes property, plant and equipment, as well as finance and operating lease right-of-use assets, by geographic region, based on where the Company conducts its operations, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Revenues ​ Long-Lived Assets ​ Year Ended December 31, ​ December 31, ​ 2025 ​ 2024 ​ 2023 ​ 2025 ​ 2024 ​ (in thousands) United States ​ $ 681,422 ​ ​ ​ $ 707,681 ​ ​ ​ $ 635,192 ​ ​ ​ $ 206,697 ​ ​ ​ $ 202,328 China ​ 3,184 ​ 4,339 ​ 4,505 ​ 110,055 ​ 107,887 France ​ 35,281 ​ 19,947 ​ 4,698 ​ 36,967 ​ 34,412 Total ​ $ 719,887 ​ $ 731,967 ​ $ 644,395 ​ $ 353,719 ​ $ 344,627 ​ ​ ​ Note 6. Customer and Supplier Concentration ​ Customer Concentrations ​ The following table provides accounts receivable and net revenue information for the Company’s three major customers: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ % of Total Accounts ​ ​ % of Net ​ ​ Receivable ​ ​ Revenues ​ ​ December 31, ​ December 31, ​ ​ Year Ended December 31, ​ ​ ​ ​ 2025 ​ ​ ​ 2024 ​ ​ ​ ​ 2025 ​ ​ ​ 2024 ​ ​ ​ 2023 McKesson 28 % 34 % ​ 24 % 25 % 25 % Cencora 28 % 23 % ​ 22 % 20 % 20 % Cardinal Health 12 % 16 % ​ 19 % 19 % 15 % ​ Supplier Concentrations ​ The Company depends on suppliers for raw materials, APIs, and other components and depends on a contract manufacturing organization, or CMO, for the supply of BAQSIMI ® that are all subject to stringent FDA requirements. Some of these materials may only be available from one or a limited number of sources. Establishing additional or replacement suppliers for these materials may take a substantial period of time, as suppliers must be approved by the FDA. Furthermore, a significant portion of raw materials may only be available from foreign sources. If the Company is unable to secure, on a timely basis, sufficient quantities of the materials it depends on to manufacture and market its products, or if the Company’s CMO is found to be non-compliant with the FDA’s or other regulatory agencies quality 119 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ system regulation, cGMP, or other applicable laws or regulations, it could have a materially adverse effect on the Company’s business, financial condition, and results of operations. ​ Note 7. Fair Value Measurements ​ GAAP defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants in the principal or most advantageous market for the asset or liability at the measurement date (an exit price). These standards also establish a hierarchy that prioritizes observable and unobservable inputs used in measuring fair value of an asset or liability, as described below: ​ ● Level 1 – Inputs to measure fair value are based on quoted prices (unadjusted) in active markets on identical assets or liabilities; ​ ● Level 2 – Inputs to measure fair value are based on the following: (a) quoted prices in active markets on similar assets or liabilities, (b) quoted prices for identical or similar instruments in inactive markets, or (c) observable (other than quoted prices) or collaborated observable market data used in a pricing model from which the fair value is derived; and ​ ● Level 3 – Inputs to measure fair value are unobservable and the assets or liabilities have little, if any, market activity; these inputs reflect the Company’s own assumptions about the assumptions that market participants would use in pricing the assets or liabilities based on best information available in the circumstances. ​ As of December 31, 2025 and 2024, cash equivalents include money market accounts and corporate and municipal bonds with original maturities of less than three months. Investments consist of certificates of deposit as well as investment-grade corporate, agency and municipal bonds with original maturity dates between three and thirty-six months. The certificates of deposit are carried at amortized cost in the Company’s consolidated balance sheets, which approximates their fair value determined based on Level 2 inputs. The corporate, agency and municipal bonds are classified as held-to-maturity and are carried at amortized cost net of allowance for credit losses. The fair value of such bonds is disclosed in Note 8 and was determined based on Level 2 inputs. The restrictions on restricted cash and investments have an immaterial effect on the fair value of these financial assets. ​ The fair values of the Company’s financial assets and liabilities measured on a recurring basis as of December 31, 2025 and 2024, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total ​ ​ ​ Level 1 ​ ​ ​ Level 2 ​ ​ ​ Level 3 ​ ​ (in thousands) Cash equivalents ​ $ 111,350 ​ $ 111,350 ​ $ — ​ $ — Restricted cash ​ ​ 235 ​ ​ 235 ​ ​ — ​ ​ — Short-term investments ​ ​ 16,530 ​ ​ — ​ ​ 16,530 ​ ​ — Restricted short-term investments ​ 2,200 ​ — ​ 2,200 ​ — Interest rate swaps related to variable rate loans ​ ​ ( 4,566 ) ​ ​ — ​ ​ ( 4,566 ) ​ ​ — Total assets and liabilities measured at fair value as of December 31, 2025 ​ $ 125,749 ​ $ 111,585 ​ $ 14,164 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total ​ ​ ​ Level 1 ​ ​ ​ Level 2 ​ ​ ​ Level 3 ​ ​ (in thousands) Cash equivalents ​ $ 102,059 ​ $ 102,059 ​ $ — ​ $ — Restricted cash ​ ​ 235 ​ ​ 235 ​ ​ — ​ ​ — Short-term investments ​ ​ 26,629 ​ ​ — ​ ​ 26,629 ​ ​ — Restricted short-term investments ​ 2,200 ​ — ​ 2,200 ​ — Interest rate swaps related to variable rate loans ​ ​ ( 234 ) ​ ​ — ​ ​ ( 234 ) ​ ​ — Total assets and liabilities measured at fair value as of December 31, 2024 ​ $ 130,889 ​ $ 102,294 ​ $ 28,595 ​ $ — 120 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ ​ The Company does not hold any Level 3 instruments that are measured at fair value on a recurring basis. ​ Nonfinancial assets and liabilities are not measured at fair value on a recurring basis but are subject to fair value adjustments in certain circumstances. These items primarily include investments in unconsolidated affiliates, long-lived assets, goodwill, and intangible assets for which the fair value is determined as part of an impairment test. As of December 31, 2025 and 2024, there were no significant adjustments to fair value for nonfinancial assets or liabilities. ​ The Company’s deferred compensation plan assets are valued using the cash surrender value of the life insurance policies and are not included in the table above. ​ Note 8. Investments ​ The following is a summary of the Company’s investments that are classified as held-to-maturity: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ ​ ​ ​ Cost ​ ​ ​ Gains ​ ​ ​ Losses ​ ​ ​ Value ​ ​ (in thousands) Corporate and agency bonds (due within 1 year) ​ $ 95,981 ​ $ 39 ​ $ ( 60 ) ​ $ 95,960 Municipal bonds (due within 1 year) ​ ​ 124 ​ ​ — ​ ​ — ​ ​ 124 Total investments as of December 31, 2025 ​ $ 96,105 ​ $ 39 ​ $ ( 60 ) ​ $ 96,084 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate and agency bonds (due within 1 year) ​ $ 42,907 ​ $ 34 ​ $ ( 25 ) ​ $ 42,916 Corporate and agency bonds (due within 1 to 3 years) ​ ​ 10,867 ​ ​ — ​ ​ ( 6 ) ​ ​ 10,861 Municipal bonds (due within 1 year) ​ ​ 199 ​ ​ — ​ ​ ( 1 ) ​ ​ 198 Total investments as of December 31, 2024 ​ $ 53,973 ​ $ 34 ​ $ ( 32 ) ​ $ 53,975 ​ At each reporting period, the Company evaluates securities for impairment when the fair value of the investment is less than its amortized cost. The Company evaluated the underlying credit quality and credit ratings of the issuers, identifying neither a significant deterioration since purchase nor any other factors that would indicate a material credit loss. ​ The Company measures expected credit losses on held-to-maturity investments on a collective basis. All the Company’s held-to-maturity investments were considered to be one pool. The estimate for credit losses considers historical loss information that is adjusted for current conditions and reasonable and supportable forecasts. Expected credit losses on held-to-maturity investments were not material to the consolidated financial statements. ​ 121 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ Note 9. Goodwill and Intangible Assets ​ The table below shows the weighted-average life, original cost, accumulated amortization, and net book value by major intangible asset classification: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ Life (Years) ​ ​ ​ Original Cost ​ ​ ​ Amortization ​ ​ ​ Net Book Value ​ ​ (in thousands) Definite-lived intangible assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ BAQSIMI ® product rights ​ 24 ​ $ 591,338 ​ $ 61,597 ​ $ 529,741 Land-use rights 39 ​ 2,540 ​ ​ 947 ​ 1,593 Other intangibles ​ 7 ​ 2,443 ​ ​ 439 ​ 2,004 Subtotal 24 ​ 596,321 ​ 62,983 ​ 533,338 Indefinite-lived intangible assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Trademark * ​ 29,225 ​ ​ — ​ 29,225 Goodwill * ​ 3,402 ​ ​ — ​ 3,402 Subtotal * ​ 32,627 ​ — ​ 32,627 As of December 31, 2025 * ​ $ 628,948 ​ $ 62,983 ​ $ 565,965 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ Life (Years) ​ ​ ​ Original Cost ​ ​ ​ Amortization ​ ​ ​ Net Book Value ​ ​ (in thousands) Definite-lived intangible assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ BAQSIMI ® product rights ​ 24 ​ $ 591,338 ​ $ 36,958 ​ $ 554,380 Land-use rights 39 ​ 2,540 ​ ​ 881 ​ 1,659 Other intangibles 7 ​ 2,443 ​ ​ 96 ​ 2,347 Subtotal 24 ​ 596,321 ​ 37,935 ​ 558,386 Indefinite-lived intangible assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Trademark * ​ 29,225 ​ — ​ 29,225 Goodwill * ​ 3,049 ​ — ​ 3,049 Subtotal * ​ 32,274 ​ — ​ 32,274 As of December 31, 2024 * ​ $ 628,595 ​ $ 37,935 ​ $ 590,660 * Intangible assets with indefinite lives have an indeterminable average life. ​ Goodwill ​ The changes in the carrying amounts of goodwill are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2025 ​ 2024 ​ (in thousands) Beginning balance $ 3,049 ​ ​ ​ $ 3,216 ​ Currency translation 353 ​ ( 167 ) ​ Ending balance $ 3,402 ​ $ 3,049 ​ ​ Amortization ​ Included in cost of revenues for the years ended December 31, 2025, 2024, and 2023 is product rights amortization expense of $ 25.0 million, $ 24.7 million, and $ 15.5 million, respectively. ​ 122 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ As of December 31, 2025, the expected amortization expense for all amortizable intangible assets during the next five fiscal years ending December 31 and thereafter is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) 2026 ​ $ 25,078 2027 ​ 25,078 2028 ​ 25,078 2029 ​ 25,078 2030 ​ 25,078 Thereafter ​ 407,948 Total amortizable intangible assets ​ 533,338 Indefinite-lived intangibles ​ 32,627 Total intangibles (net of accumulated amortization) ​ $ 565,965 ​ ​ ​ Note 10. Inventories ​ Inventories consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2025 ​ 2024 ​ (in thousands) Raw materials and supplies $ 106,832 ​ ​ ​ $ 81,511 ​ Work in process 40,440 ​ 32,807 ​ Finished goods 29,618 ​ 39,423 ​ Total inventories $ 176,890 ​ $ 153,741 ​ ​ ​ ​ Charges of $ 6.0 million, $ 14.0 million, and $ 18.8 million were included in the cost of revenues in the Company’s consolidated statements of operations for the years ended December 31, 2025, 2024, and 2023, respectively, to adjust the Company’s inventory and related firm purchase commitments to their net realizable value. For the year ended December 31, 2025, these charges included $ 0.6 million in the cost of revenues to adjust the Company’s enoxaparin inventory and related firm purchase commitments to their net realizable value. For the year ended December 31, 2024, these charges included $ 7.4 million in the cost of revenues to adjust the Company’s enoxaparin inventory and related firm purchase commitments to their net realizable value. For the year ended December 31, 2023, these charges included $ 9.1 million in the cost of revenues to adjust the Company’s enoxaparin inventory and related firm purchase commitments to their net realizable value. ​ 123 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ Note 11. Property, Plant, and Equipment ​ Property, plant, and equipment consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2025 ​ 2024 ​ (in thousands) Buildings $ 196,675 ​ ​ ​ $ 169,429 ​ Leasehold improvements 46,098 ​ 42,012 ​ Land 7,554 ​ 7,422 ​ Machinery and equipment 302,330 ​ 277,408 ​ Furniture, fixtures, and automobiles 39,769 ​ 35,976 ​ Construction in progress 24,407 ​ 36,685 ​ Total property, plant, and equipment 616,833 ​ 568,932 ​ Less accumulated depreciation ( 306,266 ) ​ ( 271,587 ) ​ Total property, plant, and equipment, net $ 310,567 ​ $ 297,345 ​ ​ The Company incurred depreciation expense of $ 31.6 million, $ 28.2 million, and $ 25.2 million for the years ended December 31, 2025, 2024, and 2023, respectively. ​ Interest expense capitalized was approximately $ 1.2 million, $ 0.8 million, and $ 2.0 million for the years ended December 31, 2025, 2024, and 2023, respectively. ​ ​ Note 12. Accounts Payable and Accrued Liabilities ​ Accounts payable and accrued liabilities consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2025 ​ 2024 ​ (in thousands) Accrued customer fees and rebates ​ $ 56,362 ​ $ 53,993 Accrued payroll and related benefits ​ ​ 26,318 ​ ​ 26,010 Accrued product returns, current portion ​ ​ 18,568 ​ ​ 14,559 Accrued loss on firm purchase commitments ​ ​ 200 ​ ​ 413 Accrued litigation and settlements ​ ​ 232 ​ ​ 8,472 Other accrued liabilities ​ ​ 14,076 ​ ​ 23,096 Total accrued liabilities ​ 115,756 ​ 126,543 Accounts payable ​ 32,592 ​ 30,514 Total accounts payable and accrued liabilities ​ $ 148,348 ​ $ 157,057 ​ ​ ​ 124 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ ​ Note 13. Debt ​ Debt consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2025 ​ 2024 ​ (in thousands) Convertible Debt ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2029 Convertible Notes ​ $ 345,000 ​ $ 345,000 ​ ​ ​ ​ ​ ​ ​ ​ ​ Term Loan ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Wells Fargo Term Loan due June 2028 ​ ​ 250,000 ​ ​ 250,000 ​ ​ ​ ​ ​ ​ ​ ​ ​ Other Loans and Payment Obligations ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ French government loans due December 2026 ​ ​ 56 ​ ​ 99 ​ ​ ​ ​ ​ ​ ​ ​ ​ Line of Credit Facilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Line of credit facility with China Merchant Bank due October 2026 ​ ​ — ​ ​ — ​ Wells Fargo Revolving line of credit facility due June 2028 ​ ​ — ​ ​ — ​ Line of credit facility with ICBC Bank due November 2033 ​ ​ 24,649 ​ ​ 18,433 ​ ​ ​ ​ ​ ​ ​ ​ ​ Equipment under Finance Leases ​ 264 ​ 432 ​ Total debt ​ 619,969 ​ 613,964 ​ Less: current portion of long-term debt ​ 1,641 ​ 234 ​ Less: loan issuance costs ​ ​ 9,579 ​ ​ 12,100 ​ Long-term debt, net of current portion and unamortized debt issuance costs ​ $ 608,749 ​ $ 601,630 ​ ​ Credit Agreement ​ 2029 Convertible Notes ​ In September 2023, the Company issued the 2029 Convertible Notes, in the aggregate principal amount of $ 345.0 million in a private offering pursuant to Section 4(a)(2) and Rule 144A under the Securities Act of 1933, as amended. The Company used portions of the net proceeds from the 2029 Convertible Notes to (i) repay approximately $ 200.0 million of the Company’s borrowings under the Wells Fargo Term Loan and (ii) repurchase $ 50.0 million of the Company’s common stock. ​ In connection with the issuance of the 2029 Convertible Notes, the Company incurred approximately $ 10.8 million of debt issuance costs, which primarily consisted of underwriting, legal and other professional fees. Unamortized debt issuance costs related to the 2029 Convertible Notes were $ 6.3 million and $ 8.3 million as of December 31, 2025 and 2024, respectively. The fair value of the 2029 Convertible Notes was approximately $ 319.1 million as of December 31, 2025 based on Level 2 inputs. ​ For the years ended December 31, 2025, 2024, and 2023, the total interest expense related to the 2029 Convertible Notes was $ 8.9 million, $ 8.9 million, and $ 2.6 million, with coupon interest expense of $ 6.9 million, $ 6.9 million, and $ 2.0 million, and the amortization of debt issuance cost of $ 2.0 million, $ 2.0 million, and $ 0.6 million, respectively. ​ The 2029 Convertible Notes are general senior, unsecured obligations and bear an interest rate of 2.0 % per year. The 125 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ 2029 Convertible Notes were issued pursuant to an indenture, dated September 15, 2023, or the Indenture, between the Company and U.S. Bank Trust Company, National Association, as trustee. ​ The 2029 Convertible Notes will rank senior in right of payment to all of the Company’s indebtedness that is expressly subordinated in right of payment to the 2029 Convertible Notes; equal in right of payment to all of the Company’s unsecured indebtedness that is not so subordinated; effectively junior to any of the Company’s secured indebtedness to the extent of the value of the assets securing such indebtedness, including any amount outstanding under the Company’s credit facilities; and structurally junior to all indebtedness and other liabilities of the Company’s current or future subsidiaries, including trade payables. ​ Interest is payable semi-annually in arrears on March 15 and September 15 of each year. The 2029 Convertible Notes may bear additional interest under specified circumstances relating to the Company’s failure to comply with its reporting obligations under the Indenture or if the 2029 Convertible Notes are not freely tradeable as required by the Indenture. ​ The 2029 Convertible Notes will mature on March 15, 2029, unless earlier converted, repurchased or redeemed. ​ Conversions of the 2029 Convertible Notes will be settled in cash up to the aggregate principal amount of the 2029 Convertible Notes to be converted, and cash, shares of common stock or a combination of cash and shares of common stock, at the Company’s election, with respect to the remainder, if any, of the Company’s conversion obligation in excess of the aggregate principal amount. ​ Holders may convert their 2029 Convertible Notes at their option prior to the close of business on the business day immediately preceding December 15, 2028, in multiples of $ 1,000 principal amount, only under the following circumstances: (i) during any calendar quarter commencing after the calendar quarter ending on December 31, 2023 (and only during such calendar quarter), if the last reported sale price of the common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130 % of the conversion price for the 2029 Convertible Notes on each applicable trading day, (ii) during the five business day period after any five consecutive trading day period in which the trading price, as defined in the Indenture, per $ 1,000 principal amount of the 2029 Convertible Notes for each trading day of the measurement period was less than 98 % of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day, (iii) if the Company calls the 2029 Convertible Notes for redemption, at any time prior to the close of business on the second scheduled trading day immediately preceding the redemption date, and (iv) upon the occurrence of specified corporate events defined in the Indenture. ​ On or after December 15, 2028, until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert all or any portion of their 2029 Convertible Notes, in multiples of $ 1,000 principal amount, at the option of the holder regardless of the foregoing circumstances. ​ The Company may redeem the 2029 Convertible Notes, at its option, in whole or in part (subject to certain limitations), on or after September 20, 2026 and prior to the 41 st scheduled trading day preceding the maturity date, if the last reported sale price of the Company’s common stock has been at least 130 % of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period (including the last trading day of such period) ending on and including the trading day immediately preceding the date on which the Company provides notice of redemption at a redemption price equal to 100 % of the principal amount of the 2029 Convertible Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. ​ The initial conversion rate is 15.8821 shares of the Company’s common stock per $ 1,000 principal amount of the 2029 Convertible Notes, which represents an initial conversion price of approximately $ 62.96 per share of common stock. The initial conversion price of $ 62.96 represents a premium of approximately 35.0 % over the last reported sale price of the Company’s common stock on Nasdaq Global Select Market on September 12, 2023. The conversion rate is subject to adjustment under certain circumstances in accordance with the terms of the Indenture. 126 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ ​ If a fundamental change, as defined in the Indenture, occurs at any time prior to the maturity date, then, subject to certain conditions, holders of the 2029 Convertible Notes may require the Company to repurchase for cash all or any portion of their 2029 Convertible Notes at a repurchase price equal to 100 % of the principal amount of the 2029 Convertible Notes to be repurchased, plus any accrued and unpaid interest. In addition, following certain specified corporate events or if the Company issues a notice of redemption, the Company will, under certain circumstances, increase the conversion rate for holders who convert their 2029 Convertible Notes in connection with such corporate event or during a redemption period. ​ Syndicated Credit Agreement with Wells Fargo Bank, National Association - Due June 2028 ​ In June 2023, in connection with the BAQSIMI ® acquisition, the Company entered into a syndicated credit agreement with Wells Fargo, or the Credit Agreement. Under the terms of the Credit Agreement, the Company borrowed $ 500.0 million in the form of a term loan, or the Wells Fargo Term Loan. Proceeds from the Wells Fargo Term Loan were used to finance the acquisition of BAQSIMI ® , repay certain of the Company’s and its subsidiaries’ existing third-party indebtedness, and pay fees and expenses incurred in connection with each of the foregoing. Outstanding borrowings with respect to the Wells Fargo Term Loan initially accrue interest, at the Company’s option, at a per annum rate equal to either (i) a base rate equal to the highest of (x) the federal funds rate, plus 0.50 %, (y) the prime rate then in effect and (z) an adjusted daily one-month Secured Overnight Financing Rate, or SOFR, rate determined on the basis of a one-month interest period plus 1.00 %, in each case, plus an applicable margin of 1.25 %, or (ii) an adjusted Term SOFR rate, subject to a floor of 0.00 %, plus an applicable margin of 2.25 %. Following delivery of financial statements for the Company’s first fiscal quarter following payment in full of a $ 125.0 million guaranteed payment owed to Lilly on June 30, 2024, the applicable margin for outstanding borrowings with respect to the Wells Fargo Term Loan will range from 0.50 % to 1.50 % in the case of base rate loans and 1.50 % to 2.50 % in the case of Term SOFR rate loans, in each case, depending on the Company’s consolidated net leverage ratio as of the most recently ended fiscal quarter. The Wells Fargo Term Loan matures in June 2028. ​ The Wells Fargo Term Loan requires principal payments of $ 12.5 million for the first year, which increases to $ 25.0 million during the second year, and $ 37.5 million during the third, fourth and fifth years, with the remaining balance due at maturity. The loan is secured by substantially all of the Company’s and certain of its subsidiaries’ assets, subject to certain exceptions and limitations. In the third quarter of 2023, the Company repaid approximately $ 200.0 million of the borrowings under the Wells Fargo term Loan with the proceeds from the 2029 Convertible Notes, thereby satisfying all of the current and future loan amortization payments required by the Wells Fargo Term Loan until maturity. In the fourth quarter of 2023, the Company made a principal payment of $ 50.0 million, reducing the balance to $ 250.0 million. ​ The Credit Agreement also provides for a $ 200.0 million Revolving Credit Facility and bears the same interest rate as the Wells Fargo Term Loan. ​ In conjunction with the Credit Agreement, the Company entered into an interest rate swap contract with Wells Fargo, with a notional amount of $ 250.0 million to exchange the variable rate on the Wells Fargo Term Loan for a fixed rate of 4.04 %. The interest swap contract liability had a fair value of $ 4.6 million as of December 31, 2025. ​ The Company incurred approximately $ 14.3 million in issuance costs in connection with the Credit Agreement, of which $ 3.0 million represented debt modification costs and were charged to interest expense in the Company’s consolidated statement of operations for year ended December 31, 2023. ​ Debt issuance costs associated with the Credit Agreement (other than its Revolving Credit Facility component) are presented as a reduction to the carrying value of the related debt, while debt issuance costs associated with the Revolving Credit Facility are capitalized within other long-term assets on the consolidated balance sheets. Unamortized debt issuance costs related to the Credit Agreement as of December 31, 2025 and 2024 were $ 4.3 million and $ 6.0 million, respectively, which are being amortized over the term of the Credit Agreement using the effective interest rate method. ​ 127 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ As a result of the $ 250.0 million repayment of the principal balance of the Wells Fargo Term Loan, approximately $ 3.8 million of unamortized debt issuance costs were written off during the year ended December 31, 2023. ​ Line of Credit Facilities ​ Line of Credit Facility with China Merchant Bank – Due October 2026 ​ In March 2020, the Company entered into a credit agreement with China Merchant Bank. The credit agreement allows the Company to borrow up to $ 14.6 million secured by buildings and land use rights held by ANP. The interest rate and other terms will be determined at the time of the borrowing, depending on the type of loan requested. The credit period was for 36 months and expired in March 2023. ​ In October 2023, the Company renewed the credit agreement with China Merchant Bank, and allows the Company to borrow up to $ 4.1 million. The credit period is for 36 months and expires in October 2026. ​ Syndicated Line of Credit Facility with ICBC Bank – Due November 2033 ​ In January 2024, the Company entered into a credit agreement with Industrial and Commercial Bank of China Limited, or ICBC Bank, acting as a lender and as agent for other lenders. The credit agreement allows the Company to borrow up to $ 40.0 million secured by equipment and buildings at ANP. The interest rate and other terms will be determined at the time of the borrowing, depending on the type of loan requested. The credit agreement expires in November 2033. ​ The loan bears interest at the prime rate as published by The People’s Bank of China minus 0.2 %. Interest payments are due quarterly and repayment of the principal amount is biannual and begins in May 2026. As of December 31, 2025, the Company had $ 24.6 million of principal outstanding under this loan, which is recorded net of loan issuance costs of $ 1.3 million. ​ Interest Rate Swap Contract ​ As of December 31, 2025, the fair value of the loans listed above approximated their carrying amount based on Level 2 inputs, with the exception of the 2029 Convertible Notes. For the Wells Fargo Term Loan, the Company has entered into a fixed interest rate swap contract to exchange the variable interest rates for fixed interest rates. The interest rate swap contract is recorded at fair value in the other long-term liabilities line in the consolidated balance sheets. Changes in the fair values of interest rate swaps were $ 4.3 million, $ 5.0 million, and $ 5.9 million for the years ended December 31, 2025, 2024, and 2023, respectively. ​ Covenants ​ At December 31, 2025 and 2024, the Company was in compliance with all of its debt covenants. ​ ​ 128 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ Long-Term Debt Maturities ​ As of December 31, 2025, the principal amounts of long-term debt maturities during each of the next five fiscal years ending December 31 are as follows: ​ ​ ​ ​ ​ ​ ​ Long-term ​ ​ Debt ​ ​ (in thousands) 2026 ​ ​ ​ $ 1,479 2027 ​ 5,692 2028 ​ 255,692 2029 ​ 353,538 2030 ​ 3,304 ​ ​ $ 619,705 ​ ​ ​ ​ Note 14. Income Taxes ​ The Company’s income (loss) before income taxes generated from its operations were: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2025 ​ 2024 ​ 2023 ​ ​ (in thousands) Income (loss) before income taxes: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ United States ​ $ 128,952 ​ $ 195,178 ​ $ 181,922 ​ Foreign ​ ( 5,328 ) ​ ( 5,414 ) ​ ( 10,563 ) ​ Total income before income taxes ​ $ 123,624 ​ $ 189,764 ​ $ 171,359 ​ ​ The Company’s provision for income taxes consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2025 ​ 2024 ​ 2023 ​ ​ (in thousands) Current provision: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ $ ( 2,874 ) ​ $ 44,251 ​ $ 42,689 ​ State ​ 227 ​ 589 ​ 1,912 ​ Foreign ​ ( 482 ) ​ 1,974 ​ 1,089 ​ Total current provision ​ ( 3,129 ) ​ 46,814 ​ 45,690 ​ Deferred provision (benefit): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ 26,338 ​ ( 17,126 ) ​ ( 13,134 ) ​ State ​ 3,402 ​ 363 ​ 1,537 ​ Foreign ​ ( 1,081 ) ​ ( 379 ) ​ ( 2,260 ) ​ Total deferred provision ​ 28,659 ​ ( 17,142 ) ​ ( 13,857 ) ​ Total provision for income taxes ​ $ 25,530 ​ $ 29,672 ​ $ 31,833 ​ ​ The lower federal current provision in 2025 reflects the impact of a tax deduction for certain previously deferred capitalized research and development expenditures under the One Big Beautiful Bill Act, or the OBBB Act. ​ For the year ended December 31, 2025, the Company adopted ASU 2023-09 on a prospective basis. ​ ​ 129 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ A reconciliation of the US federal statutory income tax rate of 21% to the Company’s effective tax rate after the adoption of ASU 2023-09 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2025 ​ ​ (in thousands) ​ Percent ​ US federal statutory tax rate $ 25,961 21.0 % State and local income taxes, net of federal income tax effect* 2,376 1.9 Foreign tax effects ​ 522 ​ 0.4 ​ Effect of cross-border tax laws ( 43 ) — Tax credits ​ ​ Research and development tax credits ( 4,464 ) ( 3.6 ) Nontaxable or nondeductible items ​ ​ ​ ​ ​ Executive compensation ​ 2,992 ​ 2.4 ​ Other ​ ( 266 ) ​ ( 0.2 ) ​ Changes in unrecognized tax benefits ​ ( 1,491 ) ​ ( 1.2 ) ​ Other adjustments ( 57 ) — Effective tax rate $ 25,530 ​ 20.7 % * State taxes in California made up the majority (greater than 50%) of the tax effect in this category. ​ A reconciliation of the US federal statutory income tax rate of 21% to the Company’s effective tax rate before the adoption of ASU 2023-09 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ ​ ​ 2024 ​ ​ ​ 2023 Statutory federal income tax ​ 21.0 % 21.0 % State tax expense, net of federal tax benefit 0.4 1.6 Foreign tax rate differences — ( 0.1 ) Foreign valuation allowance ​ 1.4 ​ 0.1 ​ Research and development credits ( 3.7 ) ( 4.2 ) Share-based compensation ( 5.1 ) ( 3.2 ) Executive compensation ​ 1.7 ​ 2.4 ​ Intercompany transfer of assets other than inventory ​ — ​ 0.6 ​ Other ( 0.1 ) 0.4 Effective tax rate ​ 15.6 % 18.6 % ​ The Company’s effective tax rate for 2025 increased in comparison to 2024 primarily due to lower excess tax benefit from share-based compensation. ​ ​ 130 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ Income Taxes Paid ​ The following table presents income taxes paid (net of refunds received) for the year ended December 31, 2025: ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2025 ​ ​ (in thousands) Federal ​ $ 20,700 State & Local ​ ​ California ​ 1,223 Other state & local jurisdictions ​ ( 611 ) Foreign ​ ​ ​ China ​ 1,504 Other foreign jurisdictions ​ ( 106 ) Total Income Taxes Paid ​ $ 22,710 ​ Deferred Tax Assets and Liabilities ​ Deferred income taxes reflect the tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes, tax credit carryforwards, and the tax effects of net operating loss carryforwards. ​ The significant components of the Company’s deferred tax assets and liabilities are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2025 ​ 2024 ​ ​ (in thousands) Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Research and development credits ​ $ 9,374 ​ $ 12,300 ​ Net operating loss carryforward ​ ​ 24,032 ​ ​ 22,047 ​ Inventory capitalization and reserve ​ 13,957 ​ 16,523 ​ Share-based compensation ​ 5,278 ​ 5,067 ​ Operating leases ​ ​ 11,028 ​ ​ 11,996 ​ Accrued expenses ​ 7,897 ​ 6,969 ​ Accrued chargebacks and rebates ​ 13,556 ​ 9,080 ​ Product return allowance ​ 6,922 ​ 5,749 ​ Intangibles ​ 2,124 ​ 2,124 ​ Research and development capitalization ​ ​ 19,967 ​ ​ 48,411 ​ Total deferred tax assets ​ 114,135 ​ 140,266 ​ Deferred tax liabilities: ​ ​ ​ ​ ​ ​ ​ Depreciation/amortization ​ 22,473 ​ 22,771 ​ Intangibles ​ 12,176 ​ 7,849 ​ Operating leases ​ ​ 10,637 ​ ​ 11,622 ​ Federal impact of state deferred taxes ​ 2,919 ​ 3,522 ​ Other ​ ​ 193 ​ ​ 984 ​ Total deferred tax liabilities ​ 48,398 ​ 46,748 ​ Valuation allowance ​ ( 23,273 ) ​ ( 22,394 ) ​ Net deferred tax assets ​ $ 42,464 ​ $ 71,124 ​ ​ Tax Law Updates ​ On July 4, 2025, the OBBB Act, was enacted into law. The OBBB Act includes significant provisions, such as the permanent extension of certain expiring provisions of the Tax Cuts and Jobs Act, modifications to the international tax 131 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ framework and the restoration of favorable tax treatment for certain business provisions. The OBBB Act did not result in any material adjustments to the Company’s total income tax provision for the year ended December 31, 2025 and the Company’s deferred tax balances were adjusted to reflect impacts of the OBBB Act enactment. ​ Net Operating Loss Carryforwards and Tax Credits ​ At December 31, 2025, the Company had no material U.S. federal or state net operating loss carryforwards, or NOL carryforwards. The Company had China, France and United Kingdom foreign NOL carryforwards of approximately $ 0.8 million, $ 91.9 million, and $ 2.9 million, respectively. The China NOL has a 5-year carryforward period and the France and United Kingdom NOLs have indefinite carryforward periods. ​ At December 31, 2025, the Company had California research and development tax credit carryforwards of approximately $ 18.8 million. The California research and development tax credit has an indefinite carryforward period. ​ Valuation Allowance ​ In assessing the need for a valuation allowance, management considers whether it is more likely than not that some portion or all of the deferred income tax assets will be realized. Ultimately, realization depends on the existence of future taxable income. Management considers sources of taxable income such as income in prior carryback periods, future reversal of existing deferred taxable temporary differences, tax-planning strategies, and projected future taxable income. ​ The Company continues to record a full valuation allowance on the net deferred income tax assets of its French subsidiary, AFP, and its U.K. subsidiaries, AUK and IMS UK and will continue to do so until the subsidiaries generate sufficient taxable income to realize their respective deferred income tax assets. As of December 31, 2025 and 2024, the Company had a full valuation allowance against the net deferred tax assets of AFP, which totaled $ 22.4 million and $ 20.7 million, respectively, and a full valuation allowance against the net deferred tax assets of its UK subsidiaries of immaterial amounts. ​ The Company also records a valuation allowance on net deferred income tax assets in states where it files separately and will continue to do so until sufficient taxable income is generated to realize these state deferred income tax assets. ​ Uncertain Income Tax Positions A reconciliation of the beginning and ending balances of unrecognized tax benefits is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2025 ​ 2024 2023 ​ ​ (in thousands) Balance at the beginning of the year ​ ​ ​ $ 13,738 ​ ​ ​ $ 12,493 ​ ​ ​ $ 12,895 Additions based on tax positions related to prior years ​ ​ 357 ​ ​ — ​ ​ — Additions based on tax positions related to the current year ​ 1,896 ​ 2,659 ​ 2,074 Deductions based on statute of limitations ​ ( 1,676 ) ​ ( 1,414 ) ​ ( 2,476 ) Balance at the end of the year ​ $ 14,315 ​ $ 13,738 ​ $ 12,493 ​ Included in the balance of unrecognized tax benefits as of December 31, 2025 and 2024, was $ 13.2 million and $ 12.7 million, respectively that represents the portion that would impact the effective income tax rate if recognized. ​ The Company recognizes interest and penalties related to unrecognized tax benefits in its income tax provision. For the years ended December 31, 2025, 2024, and 2023, the Company accrued interest of approximately $ 1.4 million, $ 1.3 million and $ 1.0 million, respectively, related to its uncertain tax positions. ​ The Company and/or one or more of its subsidiaries files income tax returns in the U.S. federal jurisdiction and various U.S. states and foreign jurisdictions. As of December 31, 2025, the Company is under U.S. federal examination for the 132 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ 2022 tax year, California for the 2019-2021 tax years, and New York for the 2023 tax year. The Company does not have a tax examination in progress for Massachusetts, other states, or foreign jurisdictions. The Company is subject to income tax audit by tax authorities for tax years 2022 to 2024 for federal, 2019 to 2024 for states, and 2015 to 2024 for foreign. ​ Note 15. Stockholders' Equity ​ Equity Plans ​ As of December 31, 2025, the Company has two equity plans: the Amended and Restated 2015 Equity Incentive Plan, or the Amended 2015 Plan, and the 2014 Employee Stock Purchase Plan or ESPP. Upon termination of the predecessor plans, the shares available for grant at the time of termination, and shares subsequently returned to the plans upon forfeiture or option termination, were transferred to the successor plan in effect at the time of share return. The Company issues new shares of common stock upon exercise of stock options, vesting of restricted stock units, or RSU, and settlement of ESPP, with the exception of the awards granted to employees at AFP, which are settled through re-issuance of the Company’s treasury shares. ​ Amended and Restated 2015 Equity Incentive Plan ​ In March 2015, the Board of Directors adopted the Company’s 2015 Equity Incentive Plan, or the Original 2015 Plan, which was approved by the Company’s stockholders in May 2015 and was set to expire in March 2025. The Original 2015 Plan was designed to meet the needs of a publicly traded company, including the requirements for granting “performance-based compensation” under Section 162(m) of the Internal Revenue Code. The Original 2015 Plan provides for the grant of incentive stock options, nonstatutory stock options, restricted stock, restricted stock units, stock appreciation rights, performance units, performance shares, and other stock or cash awards to employees of the Company and its subsidiaries, members of the Board of Directors and consultants. ​ In November 2020, the Board of Directors approved the Amendment and Restated 2015 Equity Incentive Plan to provide that at least 95 % of the shares awarded under the plan will be subject to a minimum vesting requirement of at least one year . ​ The Company initially reserved 5,000,000 shares of common stock for issuance under the Original 2015 Plan and also contained an “evergreen provision” that allowed for an annual increase in the number of shares available for issuance on January 1 of each year during the 10-year term of the 2015 Plan. ​ In February 2024, the Board of Directors approved the Company’s Amended 2015 Plan, which was subsequently approved by the Company’s stockholders, and accordingly, adopted by the Company in June 2024. The Amended 2015 Plan, among other things, extended the term of the Original 2015 Plan, increased the number of shares available for issuance under the Original 2015 Plan, and removed the evergreen provision. The term of the Amended 2015 Plan will be extended indefinitely, however, the Company’s ability to grant incentive stock options thereunder will continue through February 2034. ​ As of December 31, 2025, the Company reserved an aggregate of 6,625,746 shares of common stock for future issuance under the Amended 2015 Plan. ​ 2014 Employee Stock Purchase Plan ​ In June 2014, the Company adopted the ESPP in connection with its initial public offering. A total of 2,000,000 shares of common stock are reserved for issuance under this plan. The Company’s ESPP permits eligible employees to purchase common stock at a discount through payroll deductions during defined offering periods. Under the ESPP, the Company may specify offerings with durations of not more than 27 months, and may specify shorter purchase periods within each offering. Each offering will have one or more purchase dates on which shares of its common stock will be purchased for employees participating in the offering. An offering may be terminated under certain circumstances. The price at which 133 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ the stock is purchased is equal to 85 % of the lower of the fair market value of the common stock at the beginning of an offering period or on the date of purchase. ​ As of December 31, 2025, the Company has issued 1,443,046 shares of common stock under the ESPP and 556,954 shares of its common stock remains available for issuance under the ESPP. ​ For the years ended December 31, 2025, 2024, and 2023, the Company recorded ESPP expense of $ 1.2 million, $ 1.2 million, and $ 1.1 million, respectively. ​ Share Buyback Program ​ As of December 31, 2025, the Company’s Board of Directors have authorized a total of $ 435.0 million in the share buyback program. The primary goal of the program is to offset dilution created by the Company’s equity compensation programs. The Company’s share buyback program is expected to continue for an indefinite period of time. ​ Purchases are made through open market and private block transactions pursuant to Rule 10b5-1 plans, privately negotiated transactions or other means as determined by the Company’s management and in accordance with the requirements of the SEC and applicable laws. The timing and actual number of treasury share purchases will depend on a variety of factors including price, corporate and regulatory requirements, and other conditions. These treasury share purchases are accounted for under the cost method and are included as a component of treasury stock in the Company’s consolidated balance sheets. ​ Pursuant to the Company’s existing share buyback program, the Company purchased 2,915,580 shares, 1,919,670 shares, and 1,338,757 shares of its common stock during the years ended December 31, 2025, 2024, and 2023, for total consideration of $ 75.6 million, $ 85.5 million, and $ 58.1 million, respectively. ​ Share-Based Award Activity and Balances ​ The Company accounts for share-based compensation payments in accordance with ASC 718, which requires measurement and recognition of compensation expense at fair value for all share-based payment awards made to employees and directors. Under these standards, the fair value of option awards and the option components of the ESPP awards are estimated at the grant date using the Black-Scholes option-pricing model. The fair value of RSUs is estimated at the grant date using the Company’s common share price. The Company records share-based compensation expense net of expected forfeitures. Compensation cost for all share-based payments granted with service-based graded vesting schedules is recognized using the straight-line method over the requisite service period. ​ Options issued under the Company’s Amended 2015 Plan, and Original 2015 Plan are granted at exercise prices equal to or greater than the fair value of the underlying common shares on the date of grant and vest based on continuous service. There have been no awards with performance conditions and no awards with market conditions. The options have a contractual term of five to ten years and generally vest over a one - to five -year period. The Black-Scholes option pricing model has various inputs such as the common share price on the date of grant, exercise price, the risk-free interest rate, volatility, expected term and dividend yield, all of which are estimates. The Company records share-based compensation expense net of expected forfeitures. The change of any of these inputs could significantly impact the determination of the fair value of the Company’s options as well as significantly impact its results of operations. The significant assumptions used in the Black-Scholes option-pricing are as follows: ​ ● Determination of Fair Value of the Underlying Common Stock. For options and ESPP awards granted, the fair value for its underlying common stock is determined using the closing price on the date of grant as reported on the Nasdaq Global Select Market, or Nasdaq, with consideration of whether there is material nonpublic information that could impact that estimated fair value when it is released. ​ 134 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ ● Expected Volatility. The Company estimates its volatility based on the historical volatility of its stock price. ​ ● Expected Term. The expected term represents the period of time in which the options granted are expected to be outstanding. The Company estimates the expected term of options with consideration of vesting date, contractual term, and historical experience for exercise and post-vesting employment or contractual termination behavior after its common stock has been publicly traded. The expected term of “plain vanilla” options is estimated (using the simplified method as outlined in SAB Topic 14 because historical exercise data does not provide a reasonable basis upon which to estimate the expected term) based on the midpoint between the vesting date and the end of the contractual term under the simplified method permitted by the SEC implementation guidance. ​ ● Risk- Free Rate. The risk-free interest rate is selected based upon the implied yields in effect at the time of the option grant on U.S. Treasury zero-coupon issues with a term approximately equal to the expected life of the option being valued. ​ ● Dividends. The Company does not anticipate paying cash dividends in the foreseeable future. Consequently, the Company uses an expected dividend yield rate of zero. ​ The Company estimates forfeitures at the time of grant and revises those estimates in subsequent periods if actual experience differs from those estimates. For each of the years ended December 31, 2025, 2024, and 2023, the Company estimated an average overall forfeiture rate of approximately 7 % based on historical experience. Forfeiture rates are separately estimated for its (1) directors and officers, (2) management personnel and (3) other employees. The Company periodically assesses the forfeiture rate and the amount of expense recognized based on estimated historical forfeitures as compared to actual forfeitures. Changes in estimates are recorded in the period they are identified. ​ Tax benefits resulting from tax deductions in excess of the share-based compensation cost recognized (excess tax benefits) are recorded in the statements of cash flows as financing activities. ​ The weighted-averages for key assumptions used in determining the fair value of options granted are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ ​ 2025 ​ ​ ​ 2024 ​ ​ ​ 2023 Average volatility ​ 40.9 % 41.3 % 41.4 % Average risk-free interest rate ​ 4.2 % 4.2 % 4.1 % Weighted-average expected life in years ​ 6.2 ​ 6.2 ​ 6.2 ​ Dividend yield rate ​ — % — % — % ​ ​ 135 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ Stock Options ​ A summary of option activity under all plans for the year ended December 31, 2025, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ Remaining ​ Aggregate ​ ​ ​ ​ Exercise ​ Contractual ​ Intrinsic ​ ​ Options ​ Price ​ Term (Years) ​ Value (1) ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Outstanding as of December 31, 2024 ​ 6,655,225 ​ $ 23.75 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options granted ​ 1,206,844 ​ ​ 28.16 ​ ​ ​ ​ ​ ​ Options exercised ​ ( 946,221 ) ​ ​ 14.53 ​ ​ ​ ​ ​ ​ Options forfeited ​ ( 24,036 ) ​ ​ 33.74 ​ ​ ​ ​ ​ ​ Options expired ​ ( 7,422 ) ​ ​ 24.66 ​ ​ ​ ​ ​ ​ Outstanding as of December 31, 2025 ​ 6,884,390 ​ $ 25.75 ​ 5.30 ​ $ 33,365 ​ Exercisable as of December 31, 2025 ​ 4,731,181 ​ ​ 22.20 ​ 3.86 ​ $ 33,172 ​ Vested and expected to vest as of December 31, 2025 ​ 6,714,992 ​ ​ 25.58 ​ 5.21 ​ $ 33,365 ​ (1) The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying awards and the estimated fair value of the Company’s stock for those awards that have an exercise price below the estimated fair value at December 31, 2025. ​ During the years ended December 31, 2025, 2024, and 2023, the Company recorded expense of $ 13.1 million, $ 11.6 million, and $ 9.6 million, respectively, related to stock options granted under all plans. ​ Information relating to option grants and exercises is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2025 ​ ​ ​ 2024 ​ ​ ​ 2023 ​ (in thousands, except per share data) Weighted-average grant date fair value per share ​ $ 13.22 ​ $ 21.89 ​ $ 16.76 ​ Intrinsic value of options exercised ​ 11,559 ​ 52,068 ​ 29,918 ​ Cash received from options exercised ​ 6,388 ​ 12,239 ​ 14,172 ​ Total fair value of the options vested during the period ​ 11,917 ​ 9,818 ​ 8,890 ​ ​ A summary of the status of the Company’s non-vested options as of December 31, 2025, and changes during the year ended December 31, 2025, are presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ Grant Date ​ ​ Options ​ Fair Value Non-vested as of December 31, 2024 ​ 1,803,684 ​ $ 16.76 ​ Options granted 1,206,844 ​ ​ 13.22 ​ Options vested ( 833,283 ) ​ ​ 14.30 ​ Options forfeited ( 24,036 ) ​ ​ 15.76 ​ Non-vested as of December 31, 2025 2,153,209 ​ 15.73 ​ ​ As of December 31, 2025, there was $ 21.4 million of total unrecognized compensation cost, net of forfeitures, related to non-vested stock option based compensation arrangements granted under all plans. The cost is expected to be recognized over a weighted-average period of 2.4 years and will be adjusted for future changes in estimated forfeitures. ​ Restricted Stock Units ​ The Company grants restricted stock units, or RSUs, to certain employees and members of the Board of Directors with a vesting period of up to four years . The grantee receives one share of common stock at a specified future date for each RSU awarded. The RSUs may not be sold or otherwise transferred until vested. The RSUs do not have any voting or 136 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ dividend rights prior to the issuance of the underlying common stock. The share-based expense associated with these grants was based on the Company’s common stock fair value at the time of grant and is amortized over the requisite service period, which generally is the vesting period, using the straight-line method. During the years ended December 31, 2025, 2024, and 2023, the Company recorded expenses of $ 13.0 million, $ 11.5 million, and $ 9.5 million, respectively, related to RSU awards granted under all plans. ​ As of December 31, 2025, there was $ 22.7 million of total unrecognized compensation cost, net of forfeitures, related to non-vested RSU-based compensation arrangements granted under all plans. The cost is expected to be recognized over a weighted-average period of 2.4 years and will be adjusted for future changes in estimated forfeitures. ​ Information relating to RSU grants and deliveries is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Fair Market ​ ​ Total RSUs ​ Value of RSUs ​ ​ ​ ​ Issued ​ ​ ​ Issued (1) ​ ​ ​ ​ (in thousands) RSUs outstanding at December 31, 2024 825,421 ​ ​ ​ ​ RSUs granted 565,770 ​ $ 15,939 ​ RSUs forfeited ( 11,156 ) ​ ​ ​ ​ RSUs vested (2) ( 372,602 ) ​ ​ ​ ​ RSUs outstanding at December 31, 2025 1,007,433 ​ ​ ​ ​ (1) The total FMV is derived from the number of RSUs granted times the current stock price on the date of grant. (2) Of the vested RSUs, 140,443 shares of common stock were surrendered to fulfill tax withholding obligations. ​ Share-based Compensation Expense ​ The Company recorded share-based compensation expense, which is included in the Company’s consolidated statement of operations as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2025 ​ 2024 ​ 2023 ​ (in thousands) Cost of revenues ​ $ 6,205 ​ ​ ​ $ 5,742 ​ ​ ​ $ 4,891 ​ Operating expenses: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Selling, distribution, and marketing ​ 1,215 ​ 1,063 ​ 870 ​ General and administrative ​ 16,919 ​ 14,921 ​ 12,269 ​ Research and development ​ 2,938 ​ 2,642 ​ 2,212 ​ Total share-based compensation ​ $ 27,277 ​ $ 24,368 ​ $ 20,242 ​ ​ ​ ​ ​ ​ ​ Note 16. Employee Benefits ​ 401(k) Plan ​ The Company has a defined contribution 401(k) plan, or the Plan, whereby eligible employees voluntarily contribute up to a defined percentage of their annual compensation. The Company matches contributions at a rate of 50 % on the first 6 % of employee contributions, and pays the administrative costs of the Plan. Total employer contributions for the years ended December 31, 2025, 2024, and 2023 were approximately $ 2.6 million, $ 2.6 million, and $ 2.3 million, respectively. ​ Defined Benefit Pension Plan ​ The Company’s subsidiary, AFP, has an obligation associated with a defined-benefit plan for its eligible employees. This 137 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ plan provides benefits to the employees from the date of retirement and is based on the employee’s length of time employed by the Company. The calculation is based on a statistical calculation combining a number of factors that include the employee’s age, length of service, and AFP employee turnover rate. ​ The liability under the plan is based on a discount rate of 3.95 % and 3.40 % as of December 31, 2025 and 2024, respectively. The liability is included in other long-term liabilities in the accompanying consolidated balance sheets. The plan is currently unfunded, and the benefit obligation under the plan was $ 2.7 million and $ 2.6 million at December 31, 2025 and 2024, respectively. The Company recorded an immaterial amount of expense under the plan for each of the years ended December 31, 2025, 2024, and 2023. Gain or loss due to change in actuarial valuation of the Company’s defined benefit pension plan was not material. ​ Non-qualified Deferred Compensation Plan ​ In December 2019, the Company established a non-qualified deferred compensation plan. The plan allows certain eligible participants to defer a portion of their cash compensation and provides a matching contribution at the discretion of the Company. The plan obligations are payable upon retirement, termination of employment and/or certain other times in a lump-sum distribution or in installments, as elected by the participant in accordance with the plan. Participants can allocate their deferred compensation amongst various investment options with earnings accruing to the participant. The Company has established a Rabbi Trust to fund the plan obligations and to hold the plan assets. Eligible participants began contributing to the plan in January 2020. The plan assets were valued at approximately $ 14.5 million and $ 10.3 million as of December 31, 2025 and 2024, respectively. The plan liabilities were valued at approximately $ 15.0 million and $ 10.7 million as of December 31, 2025 and 2024, respectively. The plan assets and liabilities are included in other long-term assets and other long-term liabilities, respectively, on the Company’s consolidated balance sheets. ​ Note 17. Commitments and Contingencies ​ Lease Liabilities ​ Right-of-Use, or ROU, assets represent the Company’s right to control an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. ROU assets and liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. Lease terms are generally based on their initial non-cancelable terms, unless there is a renewal option that is reasonably certain to be exercised. Various factors, including economic incentives, intent, past history, and business needs are considered to determine if a renewal option is reasonably certain to be exercised. As most of its leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the discount rate used to present value the lease payments. The Company has lease agreements with both lease and non-lease components, which are accounted for as a single component for all asset classes. The Company leases real and personal property, in the normal course of business, under various non-cancelable operating leases. The Company, at its option, can renew a substantial portion of its leases, at the market rate, for various renewal periods ranging from one to six years . ​ ​ 138 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ The components of lease costs were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2025 ​ 2024 ​ 2023 ​ (in thousands) Operating lease costs ​ $ 9,446 ​ ​ ​ $ 6,135 ​ ​ ​ $ 5,267 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Short-term lease costs ​ ​ 544 ​ ​ 400 ​ ​ 332 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Finance lease costs ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization of right-of-use assets ​ 155 ​ 181 ​ 189 Interest on lease liabilities ​ 23 ​ 34 ​ 45 Total finance lease costs ​ $ 178 ​ $ 215 ​ $ 234 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total lease costs ​ $ 10,168 ​ $ 6,750 ​ $ 5,833 ​ Other information pertaining to leases is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ ​ 2025 ​ ​ 2024 ​ ​ 2023 ​ ​ ​ (in thousands, except lease term and discount rate) ​ Cash paid for amounts included in the measurement of lease liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating cash flows paid for operating leases ​ ​ ​ $ 8,273 ​ ​ ​ ​ $ 5,647 ​ ​ ​ ​ $ 5,106 ​ Operating cash flows paid for finance leases ​ ​ 21 ​ ​ ​ 32 ​ ​ ​ 40 ​ Financing cash flows paid for finance leases ​ ​ 151 ​ ​ ​ 161 ​ ​ ​ 154 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Right-of use assets obtained in exchange for lease liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating leases ​ ​ 2,537 ​ ​ ​ 18,804 ​ ​ ​ 10,521 ​ Finance leases ​ — ​ ​ — ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average remaining lease term (years) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating leases ​ 6.0 ​ ​ 6.6 ​ ​ 7.7 ​ Finance leases ​ 1.7 ​ ​ 2.5 ​ ​ 3.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average discount rate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating leases ​ 6.7 % ​ 6.3 % ​ 5.5 % Finance leases ​ 6.9 % ​ 6.7 % ​ 6.7 % ​ ​ 139 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ Future minimum rental payments under leases that have initial or remaining non-cancelable lease terms in excess of 12 months as of December 31, 2025, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating ​ Finance ​ ​ ​ ​ Leases ​ Leases ​ Total ​ ​ (in thousands) 2026 ​ ​ ​ $ 10,642 ​ $ 174 ​ $ 10,816 2027 ​ 9,400 ​ 104 ​ 9,504 2028 ​ 8,738 ​ — ​ 8,738 2029 ​ 8,595 ​ — ​ 8,595 2030 ​ 8,582 ​ — ​ 8,582 Thereafter ​ ​ 9,287 ​ ​ — ​ ​ 9,287 Total lease payments ​ $ 55,244 ​ $ 278 ​ $ 55,522 Less: interest ​ ​ 9,632 ​ ​ 14 ​ ​ 9,646 Total ​ $ 45,612 ​ $ 264 ​ $ 45,876 ​ New Real Estate Lease Agreement ​ In July 2025, the Company entered into an agreement to lease approximately 225,167 square feet of building space in Rancho Cucamonga, California. The non-cancelable lease term is approximately 10 years with a renewal option to extend the lease for two additional five-year periods. The monthly lease payments are $ 0.3 million subject to an annual increase of 3.25 %. The Company did not recognize any lease expense and has no ROU assets or lease liability recognized as of December 31, 2025, given that the lease commenced on January 1, 2026. ​ BAQSIMI ® ​ In connection with the BAQSIMI ® acquisition from Lilly, t he Company may also be required to pay additional contingent consideration of up to $ 450.0 million to Lilly based on the achievement of certain milestones. The Purchase Agreement provides that the contingent consideration that may become payable to Lilly would be achieved as follows: (i) a one-time payment of $ 100.0 million if the Company achieves annual net sales of $ 175.0 million or more of BAQSIMI ® and certain related products, or the Milestone Products, in any one contract year during the first five years after the Closing; (ii) up to two payments of $ 100.0 million each if the Company achieves annual net sales of $ 200.0 million or more of Milestone Products in any one contract year during the first five years after the Closing; and (iii) a one-time payment of $ 150.0 million if the Company achieves total cumulative net sales of $ 950.0 million or more of the Milestone Products for the first five years after the Closing. ​ In addition, the Company assumed certain contingent consideration of Lilly, which would require the Company to pay up to an aggregate of $ 125.0 million based on the achievement of annual net sales milestones of $ 350.0 million, $ 400.0 million and $ 600.0 million. Through December 31, 2025, the Company has not triggered any milestones and therefore no amounts have been recognized or paid. ​ Licensing Agreement with Nanjing Anji Biotechnology Co., Ltd. ​ In August 2025, the Company and Nanjing Anji Biotechnology Co., Ltd., or Anji, entered into a License Agreement, or License Agreement, pursuant to which Anji has granted the Company an exclusive license to certain intellectual property to develop, make, use and commercialize products incorporating or comprising certain compounds, including three identified products, or Licensed Products, in the United States and Canada, or the Territory. Anji has also been granted a non-exclusive license under certain intellectual property controlled by the Company to develop, make, use and commercialize Licensed Products outside the Territory. For the year ended December 31, 2025, the Company made earnest money and upfront payments for a total of $ 6.0 million, which were recorded as a research and development 140 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ expense in the Company’s consolidated statement of operations. ​ The Company is also obligated to make cash payments to Anji of up to $ 42.0 million in development-based milestone payments and up to $ 225.0 million in sales-based milestone payments, subject to the achievement of the applicable development and sales milestone events respectively, and royalty payments of 5 % on net sales, not to exceed a maximum annual amount of $ 22.5 million each calendar year for each Licensed Product and a maximum accumulated amount of $ 60.0 million for each Licensed Products. The Company is also required to pay Anji a certain percentage of sublicense income received from the sublicense transactions. The term of this License Agreement will expire, on a Licensed Product-by-Licensed Product and region-by-region basis, on the tenth anniversary of the first commercial sale of such Licensed Product in the applicable region in the Territory, with the Company having the right to extend the License Agreement until the earlier of ten additional years or the expiration, lapse, or invalidation of the last remaining valid claim of the patents licensed by Anji to the Company that covers the Licensed Products in the Territory. ​ Purchase Commitments ​ As of December 31, 2025, the Company has entered into commitments to purchase inventory and raw materials for an aggregate amount of approximately $ 37.5 million. ​ Note 18. Related-Party Transactions ​ Hanxin Pharmaceutical Technology, Co., Ltd. ​ The Company has an 11.5 % ownership in Hanxin that is accounted for as an equity method investment. The Company maintains a seat on Hanxin’s board of directors, and Henry Zhang, the son of Dr. Jack Zhang, is an equity holder, the general manager, and the chairman of the board of directors of Hanxin. Additionally, Dr. Mary Luo and Dr. Jack Zhang, have an ownership interest in Hanxin through an affiliated entity. As a result, Hanxin is a related party. ​ Contract Manufacturing Agreements with Hanxin The Company has various contract manufacturing agreements with Hanxin and its subsidiaries, whereby Hanxin will develop several active pharmaceutical ingredients and finished products for the Chinese market and will engage the Company to manufacture the products on a cost-plus basis. In January 2026, the Company amended the contract manufacturing agreement with Hanxin, whereby, the amendment now expands the territory of the Manufacturing Agreement with the addition of a global territory, with the exception of the United States and Canada for Lidocaine and Cotricotropin, as well as a global territory for API of Semaglutide, and a global territory for Finished Product of Semaglutide tablet with dose 3, 7 and 14 milligrams. Additionally, the amendment clarifies the intellectual property rights and adds indemnification and limitation of liability terms. During the years ended December 31, 2025, 2024, and 2023, the Company recognized $ 1.1 million, $ 0.5 million and $ 0.1 million of revenue from manufacturing services provided to Hanxin, respectively. As of December 31, 2025, the Company had an immaterial amount of receivables from Hanxin under these agreements. Contract Research Agreement with Hanxin ​ The Company entered into various contract research agreements with Hanxin, a related party, whereby Hanxin will develop Recombinant Human Insulin Research Cell Banks and Recombinant Peptide Research Cell Banks, or RCBs, for the Company and license the RCBs to the Company subject to a fully paid, exclusive, perpetual, transferable, sub-licensable worldwide license. Hanxin will also perform scale-up manufacturing process development using the RCBs for the Company. ​ During the years ended December 31, 2025, 2024, and 2023, the Company paid $ 0.4 million, $ 0.2 million and $ 1.6 million, respectively, under this agreement. As of December 31, 2025, the Company had an immaterial amount of 141 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ payable to Hanxin under this agreement. ​ Supply Agreement with Letop ​ In November 2022, the Company entered into a supply agreement with Nanjing Letop Biotechnology Co., Ltd., or Letop, which is considered a related-party due to an ownership stake of Henry Zhang. Under the terms of the supply agreement, Letop will manufacture and deliver chemical intermediates to the Company on a cost-plus basis. The agreement is effective for three years and the total cost of the agreement shall not exceed $ 1.5 million, with payments adjusted based on the then current exchange rates. ​ During the years ended December 31, 2025 and 2024, the Company paid an immaterial amount under this agreement. During the year ended December 31, 2023, the Company paid $ 0.7 million under this agreement. As of December 31, 2025, the Company did no t have any additional accruals payable to Letop. ​ Primatene MIST ® Distribution Agreement with Hong Kong Genreach Limited ​ In August 2024, the Company entered into a distribution agreement with Hong Kong Genreach Limited, or Genreach, a wholly owned subsidiary of Hanxin, a related party. Per the terms of the agreement, the Company has appointed Genreach as the exclusive distributor to market and sell Primatene MIST ® in Mainland China, Taiwan, Hong Kong, and Macau in the Greater China region. Genreach will be responsible for obtaining any and all regulatory approvals in the region for Primatene MIST ® . ​ In January 2026, Armstrong and Genreach amended the distribution agreement to expand the region of the distribution agreement to include the Middle East countries and Southeast Asia, as well as amending the annual minimum purchase amount. ​ The term of the agreement is for ten years, with both parties having termination rights without cause after the completion of the second contract year. ​ During the year ended December 31, 2025, the Company did no t recognize any revenue from the distribution agreement. During the year ended December 31, 2024, the Company recognized $ 1.1 million of revenue from the distribution agreement with Genreach. As of December 31, 2025, the Company did no t have any receivables from Genreach. ​ BAQSIMI ® Distribution Agreement with Nanjing Chengong Pharmaceutical Co., Limited. ​ In October 2025, the Company entered into a distribution agreement with Nanjing Chengong Pharmaceutical Co., Limited, or Chengong, a wholly-owned subsidiary of Hanxin, a related party. Per the terms of the agreement, the Company will collaborate with Chengong to expand distribution of BAQSIMI ® , in Mainland China, Taiwan, Hong Kong, and Macau in the Greater China region, and appoint Chengong as the exclusive distributor to market and sell BAQSIMI ® in the Greater China Region. Chengong is responsible for obtaining any and all regulatory approvals in the Region, and performing the required post marketing clinical trials for BAQSIMI ® . ​ The term of the agreement is for ten years , with both parties having termination rights without cause after the completion of the fourth contract year. ​ During the year ended December 31, 2025, the Company did no t recognize any revenue from the distribution agreement. As of December 31, 2025, the Company did no t have any receivables from Chengong. ​ 142 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ ​ Note 19. Litigation ​ Employee Litigation Matters ​ On April 15, 2024, a former employee initiated an employment litigation against Amphastar and IMS by filing a complaint, as amended, having individual and class action claims for alleged violations of the California Labor Code pertaining to California’s Private Attorneys General Act, or PAGA, wage and hour, and other state laws. This complaint was filed in the Superior Court of California for the County of Los Angeles. In the complaint, the plaintiff is seeking damages and related remedies under California law, as well as various penalty payments under the California Labor Code. In November 2024, the court ordered the plaintiff to dismiss the individual and class claims, with only the PAGA claim remaining. The Company intends to vigorously defend itself against the complaint. ​ On June 20, 2024, a former employee initiated an employment litigation against Amphastar, IMS and Roth Staffing Companies L.P. by filing a complaint having individual and class action claims for alleged violations of the California Labor Code pertaining to wage and hour, and other state laws. This complaint was filed in the Superior Court of California for the County of Los Angeles. In the complaint, the plaintiff is seeking damages and related remedies under California law, as well as various penalty payments under the California Labor Code. The Company intends to vigorously defend itself against the complaint. ​ On October 30, 2025, a former employee initiated a class action litigation against Amphastar and IMS by filing a complaint for alleged violations of the California Labor Code pertaining to California’s PAGA, wage and hour, and other state laws. This complaint was filed in the Superior Court of California for the County of Los Angeles. In the complaint, the plaintiff is seeking damages and related remedies under California law, as well as various penalty payments under the California Labor Code. The Company intends to vigorously defend itself against the complaint. ​ Other Litigation Matters ​ On August 23, 2023, the Company was subject to a personal injury lawsuit. A jury trial was held in the Superior Court of California, for the County of San Bernardino from September 2025 to October 2025. On October 22, 2025, the jury returned a verdict awarding the plaintiff $ 34.1 million, of which $ 11.0 million was covered by the Company’s insurance policies. The remaining $ 23.1 million was recorded within general and administrative expenses in the Company’s consolidated statement of operations for the year ended December 31, 2025. The Company entered into a settlement agreement with the plaintiff in November 2025 pursuant to which the settlement amount based on the jury verdict was paid by the Company in the fourth quarter of 2025. ​ The Company is also subject to various other claims, arbitrations, investigations, and lawsuits from time to time arising in the ordinary course of business. In addition, third parties may, from time to time, assert claims against the Company in the forms of letters and other communications. ​ The Company records a provision for contingent losses when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. In the opinion of management, the ultimate resolution of any such matters is not expected to have a material adverse effect on its financial position, results of operations, or cash flows; however, the results of litigation and claims are inherently unpredictable and the Company’s view of these matters may change in the future. Regardless of the outcome, litigation can have an adverse impact on the Company because of defense and settlement costs, diversion of management resources, and other factors. ​ 143 Table of Contents AMPHASTAR PHARMACEUTICALS, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS ​ Note 20. Subsequent Events Licensing Agreement with Hanxin In January 2026, the Company and Hanxin, a related party, entered into a license agreement pursuant to which Hanxin has granted the Company an exclusive license to certain intellectual property controlled by Hanxin to develop, make, use and commercialize products incorporating or comprising of corticotropin compound, or corticotropin, in the United States and Canada, or the Territory. Hanxin has also granted a non-exclusive license under certain intellectual property controlled by the Company to develop, make, use and commercialize corticotropin outside the Territory. As part of the agreement, the Company made an upfront payment of $ 2.0 million to Hanxin upon signing. The Company is also obligated to make cash payments to Hanxin of up to $ 14.0 million in development milestone payments and up to $ 75.0 million in sales milestone payments, subject to the achievement of the applicable development and sales milestone events respectively, and royalty payments of 5 % on net sales, not to exceed a maximum annual amount of $ 7.5 million each calendar year and a maximum accumulated amount of $ 60.0 million for corticotropin. Hanxin will pay to the Company a royalty payment of net sales of corticotropin that are based on any patents licensed by the Company to Hanxin under the License Agreement or regulatory exclusivity covering corticotropin. The term of the license agreement will expire, region-by-region basis, on the tenth anniversary of the first commercial sale of corticotropin in the applicable region, with the Company having the right to extend the license agreement until the earlier of ten additional years or the expiration, lapse, or invalidation of the last remaining valid claim of the patents licensed by Hanxin to the Company that covers the product. ​ 144 Table of Contents Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure. None.