Altimmune, Inc. 10-Q

Item 1. Financial Statements ALTIMMUNE, INC. CONSOLIDATED BALANCE SHEETS (In thousands, except share and per-share amounts) ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ ​ 2024 ​ 2023 ​ ​ (Unaudited) ​ ​ ​ ASSETS ​ ​ ​ Current assets: ​ ​ Cash and cash equivalents ​ $ 78,978 ​ $ 135,117 Restricted cash ​ 41 ​ 41 Total cash, cash equivalents and restricted cash ​ 79,019 ​ 135,158 Short-term investments ​ 103,046 ​ 62,698 Accounts and other receivables ​ 307 ​ 1,111 Income tax and R&D incentive receivables ​ 2,272 ​ 3,742 Prepaid expenses and other current assets ​ 2,871 ​ 6,917 Total current assets ​ 187,515 ​ 209,626 Property and equipment, net ​ 544 ​ 651 Other assets ​ 299 ​ 363 Total assets ​ $ 188,358 ​ $ 210,640 LIABILITIES AND STOCKHOLDERS’ EQUITY ​ ​ Current liabilities: ​ ​ Accounts payable ​ $ 3,760 ​ $ 2,070 Accrued expenses and other current liabilities ​ 7,573 ​ 10,073 Total current liabilities ​ 11,333 ​ 12,143 Noncurrent liabilities ​ 4,088 ​ 4,398 Total liabilities ​ 15,421 ​ 16,541 Commitments and contingencies (Note 10) ​ ​ Stockholders’ equity: ​ ​ Common stock, $ 0.0001 par value; 200,000,000 shares authorized; 70,899,134 and 70,677,400 shares issued and outstanding as of March 31, 2024 and December 31, 2023, respectively ​ ​ 7 ​ ​ 7 Additional paid-in capital ​ 668,816 ​ 665,427 Accumulated deficit ​ ( 490,725 ) ​ ( 466,331 ) Accumulated other comprehensive loss, net ​ ( 5,161 ) ​ ( 5,004 ) Total stockholders’ equity ​ 172,937 ​ 194,099 Total liabilities and stockholders’ equity ​ $ 188,358 ​ $ 210,640 ​ The accompanying notes are an integral part of the unaudited consolidated financial statements. ​ 1 Table of Contents ALTIMMUNE, INC. CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) (In thousands, except share and per-share amounts) ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ March 31, ​ 2024 2023 Revenues $ 5 ​ $ 21 Operating expenses: ​ Research and development 21,487 ​ 17,249 General and administrative 5,312 ​ 4,531 Total operating expenses 26,799 ​ 21,780 Loss from operations ( 26,794 ) ​ ( 21,759 ) Other income (expense): ​ Interest expense ( 1 ) ​ ( 2 ) Interest income 2,413 ​ 1,668 Other income (expense), net ( 12 ) ​ 19 Total other income (expense), net 2,400 ​ 1,685 Net loss ( 24,394 ) ​ ( 20,074 ) Other comprehensive income — unrealized (loss) gain on short-term investments ( 157 ) ​ 126 Comprehensive loss $ ( 24,551 ) ​ $ ( 19,948 ) Net loss per share, basic and diluted $ ( 0.34 ) ​ $ ( 0.40 ) Weighted-average common shares outstanding, basic and diluted 70,801,713 ​ 50,125,685 ​ The accompanying notes are an integral part of the unaudited consolidated financial statements. ​ ​ 2 Table of Contents ​ ALTIMMUNE, INC. CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY (Unaudited) (In thousands, except share amounts) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Additional ​ ​ ​ ​ Other ​ Total ​ Common Stock Paid-In Accumulated Comprehensive Stockholders’ ​ ​ Shares ​ Amount ​ Capital ​ Deficit ​ Loss ​ Equity Balance at December 31, 2023 ​ 70,677,400 ​ $ 7 ​ $ 665,427 ​ $ ( 466,331 ) ​ $ ( 5,004 ) ​ $ 194,099 Stock-based compensation — ​ — ​ 3,650 ​ — ​ — ​ 3,650 Exercise of stock options 1,250 ​ — ​ 9 ​ — ​ — ​ 9 Vesting of restricted stock awards including withholding, net ​ 107,875 ​ ​ — ​ ​ ( 600 ) ​ ​ — ​ ​ — ​ ​ ( 600 ) Issuance of common stock from Employee Stock Purchase Plan 62,609 ​ — ​ 169 ​ — ​ — ​ 169 Issuance of common stock upon exercise of warrants ​ 50,000 ​ ​ — ​ ​ 161 ​ ​ — ​ ​ — ​ ​ 161 Unrealized (loss) gain on short-term investments — ​ — ​ — ​ — ​ ( 157 ) ​ ( 157 ) Net loss ​ — ​ ​ — ​ ​ — ​ ​ ( 24,394 ) ​ ​ — ​ ​ ( 24,394 ) Balance at March 31, 2024 70,899,134 $ 7 $ 668,816 $ ( 490,725 ) $ ( 5,161 ) $ 172,937 ​ The accompanying notes are an integral part of the unaudited consolidated financial statements. ​ 3 Table of Contents ​ ​ ALTIMMUNE, INC. CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY (Unaudited) (In thousands, except share amounts) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Additional ​ ​ ​ ​ Other ​ Total ​ Common Stock Paid-In Accumulated Comprehensive Stockholders’ ​ ​ Shares ​ Amount ​ Capital ​ Deficit ​ Loss ​ Equity Balance at December 31, 2022 ​ 49,199,845 ​ $ 5 ​ $ 568,399 ​ $ ( 377,884 ) ​ $ ( 5,227 ) ​ $ 185,293 Stock-based compensation — ​ — ​ 2,675 ​ — ​ — ​ 2,675 Exercise of stock options 19,303 ​ — ​ 61 ​ — ​ — ​ 61 Vesting of restricted stock awards including withholding, net 54,347 ​ ​ — ​ ​ ( 484 ) ​ ​ — ​ ​ — ​ ( 484 ) Issuance of common stock from Employee Stock Purchase Plan 13,215 ​ — ​ 135 ​ — ​ — ​ 135 Unrealized (loss) gain on short-term investments — ​ — ​ — ​ — ​ 126 ​ 126 Net loss ​ — ​ ​ — ​ ​ — ​ ​ ( 20,074 ) ​ ​ — ​ ​ ( 20,074 ) Balance at March 31, 2023 49,286,710 $ 5 $ 570,786 $ ( 397,958 ) $ ( 5,101 ) $ 167,732 ​ The accompanying notes are an integral part of the unaudited consolidated financial statements. ​ 4 Table of Contents ​ ALTIMMUNE, INC. CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (In thousands) ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, ​ ​ 2024 ​ 2023 CASH FLOWS FROM OPERATING ACTIVITIES: ​ ​ Net loss ​ $ ( 24,394 ) ​ $ ( 20,074 ) Adjustments to reconcile net loss to net cash used in operating activities: ​ ​ ​ Stock-based compensation expense ​ 3,650 ​ 2,675 Depreciation of property and equipment ​ 107 ​ 125 Accretion of discounts on short-term investments ​ ​ ( 983 ) ​ ​ ( 481 ) Loss (gain) on foreign currency exchange ​ 8 ​ ( 18 ) Changes in operating assets and liabilities: ​ ​ ​ ​ Accounts receivable ​ 804 ​ ( 80 ) Prepaid expenses and other assets ​ 4,046 ​ 1,589 Accounts payable ​ 1,690 ​ 434 Accrued expenses and other liabilities ​ ( 2,755 ) ​ ( 2,827 ) Income tax and R&D incentive receivables ​ 1,470 ​ ( 750 ) Net cash used in operating activities ​ ( 16,357 ) ​ ( 19,407 ) CASH FLOWS FROM INVESTING ACTIVITIES: ​ ​ Proceeds from sales and maturities of short-term investments ​ 14,000 ​ 34,565 Purchases of short-term investments ​ ( 53,521 ) ​ ( 21,212 ) Purchases of property and equipment, net ​ — ​ ( 51 ) Net cash (used in) provided by investing activities ​ ( 39,521 ) ​ 13,302 CASH FLOWS FROM FINANCING ACTIVITIES: ​ ​ Payments of deferred offering costs ​ ​ — ​ ​ ( 13 ) Proceeds from exercises of warrants ​ 161 ​ — Proceeds from issuance of common stock from Employee Stock Purchase Plan ​ 169 ​ 135 Proceeds from exercises of stock options ​ 9 ​ 61 Payments for tax withholding in share-based compensation ​ ( 600 ) ​ ( 485 ) Net cash used in financing activities ​ ( 261 ) ​ ( 302 ) Net decrease in cash and cash equivalents and restricted cash ​ ( 56,139 ) ​ ( 6,407 ) Cash, cash equivalents and restricted cash at beginning of period ​ 135,158 ​ 111,131 Cash, cash equivalents and restricted cash at end of period ​ $ 79,019 ​ $ 104,724 ​ ​ ​ ​ ​ ​ ​ SUPPLEMENTAL NON-CASH ACTIVITIES: ​ ​ ​ ​ Deferred offering costs in accrued expenses and other current liabilities ​ $ — ​ $ 182 ​ The accompanying notes are an integral part of the unaudited consolidated financial statements. ​ 5 Table of Contents ALTIMMUNE, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Unaudited) 1. Nature of Business and Basis of Presentation Nature of Business Altimmune, Inc., headquartered in Gaithersburg, Maryland, United States, together with its subsidiaries (collectively, the “Company” or “Altimmune”) is a clinical stage biopharmaceutical company incorporated under the laws of the State of Delaware. The Company is focused on developing treatments for obesity and liver diseases. The Company’s lead product candidate, pemvidutide (formerly known as ALT-801), is a novel, investigational, peptide-based GLP-1/glucagon dual receptor agonist in development for the treatment of obesity and metabolic dysfunction-associated steatohepatitis (“MASH”), previously termed non-alcoholic steatohepatitis (“NASH”). Since its inception, the Company has devoted substantially all of its efforts to business planning, research and development, recruiting management and technical staff and raising capital, and has financed its operations through the issuance of common and preferred stock, long-term debt and proceeds from research grants and government contracts. The Company has not generated any revenues from the sale of any products to date, and there is no assurance of any future revenues from product sales. Basis of Presentation The accompanying unaudited consolidated financial statements are prepared pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Accordingly, they do not include all of the information and disclosures required by accounting principles generally accepted in the United States (“U.S. GAAP”) for complete consolidated financial statements and should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2023 included in the Annual Report on Form 10-K which was filed with the SEC on March 27, 2024. In the opinion of management, the Company has prepared the accompanying unaudited consolidated financial statements on the same basis as the audited consolidated financial statements, and these consolidated financial statements include all adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the results of the interim periods presented. The operating results for the interim periods presented are not necessarily indicative of the results expected for the full year 2024 or any future years or periods. The accompanying unaudited consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation. The accompanying unaudited consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets, and the satisfaction of liabilities in the ordinary course of business. The financial statements do not include any adjustments relating to the recoverability and classification of recorded assets and liabilities that might be necessary should the Company be unable to continue as a going concern. 2. Summary of Significant Accounting Policies During the three months ended March 31, 2024, there have been no significant changes to the Company’s summary of significant accounting policies contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 as filed with the SEC on March 27, 2024. 6 Table of Contents Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant estimates and assumptions made in the accompanying condensed consolidated financial statements include, but are not limited to, the valuation of share-based awards, income taxes, and accruals for research and development activities. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable. However, actual results could differ from those estimates. Income Taxes Due to a full valuation allowance, the Company did not record an income tax expense (benefit) for either of the three months ended March 31, 2024 or 2023. The Company calculates its quarterly income tax provision based on estimated, annual effective tax rates applied to ordinary income (or loss) and other known items computed and recognized as they occur. The Company’s total provision is based on the United States statutory rate, increased by state and foreign taxes and reduced by a full valuation allowance on the Company’s deferred tax assets. 3. Fair Value Measurements The Company’s assets measured at fair value on a recurring basis as of March 31, 2024 consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement at March 31, 2024 ​ Total Level 1 Level 2 Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents - money market funds ​ $ 64,938 ​ $ 64,938 ​ $ — ​ $ — Short-term investments ​ 103,046 ​ — ​ 103,046 ​ — Total ​ $ 167,984 ​ $ 64,938 ​ $ 103,046 ​ $ — ​ The Company’s assets measured at fair value on a recurring basis as of December 31, 2023 consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement at December 31, 2023 ​ Total Level 1 Level 2 Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents - money market funds ​ $ 123,233 $ 123,233 ​ $ — ​ $ — Short-term investments ​ 62,698 ​ — ​ 62,698 ​ — Total ​ $ 185,931 ​ $ 123,233 ​ $ 62,698 ​ $ — ​ ​ Short-term investments have been initially valued at the transaction price and subsequently valued at the end of each reporting period utilizing third party pricing services or other market observable data (Level 2). The pricing services utilize industry standard valuation models, including both income and market-based approaches and observable market inputs to determine value. Short-term investments with quoted prices as of March 31, 2024 as shown below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 ​ ​ Amortized Cost ​ Unrealized (Loss) Gain ​ Credit loss ​ Market Value United States treasury securities $ 20,583 $ ( 28 ) $ — $ 20,555 Commercial paper and corporate debt securities ​ ​ 63,275 ​ ​ ( 83 ) ​ ​ — ​ ​ 63,192 Asset backed securities ​ 8,439 ​ ( 9 ) ​ — ​ 8,430 Agency debt securities ​ ​ 10,870 ​ ​ ( 1 ) ​ ​ — ​ ​ 10,869 Total ​ $ 103,167 ​ $ ( 121 ) ​ $ — ​ $ 103,046 ​ 7 Table of Contents Short-term investments with quoted prices as of December 31, 2023 as shown below (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ ​ Amortized Cost ​ Unrealized (Loss) Gain ​ Credit Loss ​ Market Value United States treasury securities $ 19,472 $ 12 $ — $ 19,484 Commercial paper and corporate debt securities ​ ​ 31,301 ​ ​ 24 ​ ​ — ​ ​ 31,325 Asset backed securities ​ 2,966 ​ ( 4 ) ​ — ​ 2,962 Agency debt securities ​ ​ 8,923 ​ ​ 4 ​ ​ — ​ ​ 8,927 Total ​ $ 62,662 ​ $ 36 ​ $ — ​ $ 62,698 ​ As of March 31, 2024 and December 31, 2023, none of the unrealized losses on the Company’s short-term investments are a result of credit loss, and therefore, any unrealized losses were recognized in OCI. As of March 31, 2024 and December 31, 2023, the Company had $ 0.2 million and $ 0.1 million, respectively, accrued interest on short-term investments included in “Accounts and other receivables” on the accompanying Consolidated Balance Sheets. Separate disclosure is required for assets and liabilities measured at fair value on a recurring basis from those measured at fair value on a non-recurring basis. Assets recorded at fair value on a non-recurring basis, such as property and equipment and intangible assets are recognized at fair value when they are impaired. During the three months ended March 31, 2024 and year ended December 31, 2023, the Company had no significant assets or liabilities that were measured at fair value on a non-recurring basis. 4. Operating Leases The Company’s operating leases consist of leases for office and laboratory space in the United States, which expire in April 2025. Rent expense under these leases during each of the three months ended March 31, 2024 and 2023 was $ 0.2 million. Rent expense includes short-term leases and variable lease costs that are not included in the lease obligation. Short-term leases are leases having a term of twelve months or less. The Company recognizes short-term leases on a straight-line basis and does not record a related lease asset or liability for such leases. The office space lease provides for increases in future minimum annual rental payments as defined in the lease agreements. The office space lease also includes an option to renew the lease as of the end of the term. The Company has determined that the lease renewal option is not reasonably certain of being exercised. The cash paid for operating lease liabilities for each of the three months ended March 31, 2024 and 2023 was $ 0.1 million. Supplemental other information related to the operating leases balance sheet information is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 ​ December 31, 2023 Operating lease obligations (see Note 5 and 6) $ 552 $ 671 ​ Operating lease right-of-use assets (included in "Other assets" in Balance Sheet) ​ $ 300 ​ $ 363 ​ Weighted-average remaining lease term (years) ​ 1.1 ​ 1.3 ​ Weighted-average discount rate ​ 7.2 % 7.2 % ​ ​ 8 Table of Contents 5. Accrued Expenses Accrued expenses and other current liabilities consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 ​ December 31, 2023 Accrued professional services $ 305 $ 293 Accrued payroll and employee benefits ​ 1,038 ​ 3,315 Accrued research and development ​ 5,656 ​ 5,845 Lease obligation, current portion (see Note 4) ​ 508 ​ 496 Accrued interest and other ​ 66 ​ 124 Total accrued expenses and other current liabilities ​ $ 7,573 ​ $ 10,073 ​ ​ ​ 6. Noncurrent Liabilities The Company’s noncurrent liabilities are summarized as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 ​ December 31, 2023 Research and development incentive credit ​ $ 3,847 ​ $ 4,023 Lease obligation, long-term portion (see Note 4) ​ 44 ​ 175 Conditional economic incentive grants ​ 160 ​ 160 Other ​ 37 ​ 40 Total noncurrent liabilities ​ $ 4,088 ​ $ 4,398 ​ ​ 7. Stockholders’ Equity The Amended and Restated Certificate of Incorporation, as amended (“Charter”), authorizes the Company to issue 200,000,000 shares of common stock, par value $ 0.0001 per share. As of March 31, 2024, the Company had 70,899,134 shares of common stock issued and outstanding . Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are not entitled to receive dividends, unless declared by the board of directors. The Charter also authorizes the Company to issue 1,000,000 shares of preferred stock, par value $ 0.0001 per share. As of March 31, 2024, the Company had no shares of preferred stock issued and outstanding . At-the-Market Offerings On February 28, 2023, the Company entered into an Equity Distribution Agreement (the “2023 Agreement”) with Evercore Group L.L.C., JMP Securities LLC and B. Riley Securities, Inc., serving as sales agents (the “Sales Agents”) with respect to an at-the-market offerings program under which the Company may offer and sell, from time to time at its sole discretion, shares of its common stock, having an aggregate offering price of up to $ 150.0 million (the “Shares”) through the Sales Agents (the “2023 Offering”). All Shares offered and sold in the 2023 Offering will be issued pursuant to the Company’s Registration Statement on Form S-3 filed with the SEC on February 28, 2023, which was declared effective immediately, the prospectus supplement relating to the 2023 Offering filed with the SEC on February 28, 2023 and any applicable additional prospectus supplements related to the 2023 Offering that form a part of the Registration Statement. The Company capitalized approximately $ 0.2 million of other offering costs which will offset the proceeds received from the shares sold under the 2023 Agreement. Since inception through March 31, 2024, the Company has sold 20,454,516 shares of common stock under the 2023 Agreement resulting in approximately $ 86.6 million in proceeds, net of $ 2.8 million commission and other offering costs. No shares were sold under the 2023 Agreement during the three months ended March 31, 2024, and as of March 31, 2024, $ 60.6 million remained available to be sold under the 2023 Agreement. As of March 31, 2024, there was $ 0.1 million deferred offering costs included in prepaid expenses and other current assets on the accompanying consolidated balance sheets. 9 Table of Contents Warrants On March 5, 2024, warrant holders exercised 50,000 warrants with an exercise price of $ 3.21 , resulting in the issuance of 50,000 shares of common stock. As of March 31, 2024, the Company had no outstanding warrants. ​ 8. Stock-Based Compensation 2017 Omnibus Incentive Plan (Omnibus Plan) The Company’s Omnibus Plan provides for an annual increase on January 1 of each year commencing in 2019 and ending on and including January 1, 2027 up to an amount equal to the lowest of (i) 4 % of the total number of shares of common stock outstanding on a fully diluted basis as of December 31 of the immediately preceding calendar year, and (ii) such number of shares of common stock, if any, determined by the Company’s board of directors. Accordingly, on January 1, 2024, the number of shares of Common Stock reserved and available for issuance under the Omnibus Plan increased by 3,055,006 shares of common stock. Stock Options The Company’s stock option awards generally vest over four years and typically have a contractual life of ten years . As of March 31, 2024, there was $ 24.2 million of unrecognized compensation cost related to stock options, which is expected to be recognized over a weighted-average period of 3.0 years. During the three months ended March 31, 2024, the Company granted 1,566,575 stock options with a weighted average exercise price of $ 9.32 and per share weighted average grant date fair value of $ 7.55 . Information related to stock options outstanding as of March 31, 2024 is as follows (in thousands, except share, exercise price and contractual term): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ ​ ​ ​ ​ ​ Weighted- ​ Remaining ​ ​ ​ ​ ​ Number of ​ Average ​ Contractual Term ​ Aggregate Intrinsic ​ ​ Stock Options ​ Exercise Price ​ (Years) ​ Value (In thousands) Outstanding, December 31, 2023 5,043,593 ​ $ 9.33 5.9 ​ $ 16,919 Granted 1,566,575 ​ $ 9.32 ​ Exercised ( 1,250 ) ​ $ 7.05 ​ Forfeited or expired ( 68,211 ) ​ $ 7.06 ​ Outstanding, March 31, 2024 6,540,707 ​ $ 9.35 6.0 ​ $ 15,079 Exercisable, March 31, 2024 2,943,720 ​ $ 9.18 5.9 ​ $ 9,115 Vested and expected to vest, March 31, 2024 6,216,978 ​ $ 9.34 6.0 ​ $ 14,542 ​ Restricted Stock Units (RSUs) During the three months ended March 31, 2024, the Company granted 484,600 shares of RSUs with a weighted average grant date fair value of $ 9.32 which vest over four years . As of March 31, 2024, the Company had unvested RSUs of 902,952 shares with total unrecognized compensation expense of $ 7.9 million, which the Company expects to recognize over a weighted average period of approximately 3.1 years. During the three months ended March 31, 2024, the Company issued 107,875 shares of unrestricted common stock as a result of the vesting of 169,315 RSUs net of 61,440 shares of common stock withheld to satisfy tax withholding obligations. 2019 Employee Stock Purchase Plan Under the Employee Stock Purchase Plan, employees purchased 62,609 shares for $ 0.2 million during the three months ended March 31, 2024. 10 Table of Contents Stock-based Compensation Expense Stock-based compensation expense is classified in the unaudited consolidated statements of operations and comprehensive loss for the three months ended March 31, 2024 and 2023 as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, ​ ​ 2024 2023 Research and development ​ $ 1,675 ​ $ 1,187 General and administrative ​ 1,975 ​ 1,488 Total ​ $ 3,650 ​ $ 2,675 ​ ​ ​ 9. Net Loss Per Share Because the Company has reported net loss attributable to common stockholders for the three months ended March 31, 2024 and 2023, basic and diluted net loss per share attributable to common stockholders in each period are the same. Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average numbers of shares of common stock outstanding for the period. Diluted net loss per share is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period. As such, all unvested restricted stock, RSUs, common stock and stock options have been excluded from the computation of diluted weighted average shares outstanding because such securities would have an anti-dilutive impact for all periods presented. Potential common shares issuable upon conversion, vesting or exercise of unvested restricted stock, RSUs, common stock warrants, and stock options that are excluded from the computation of diluted weighted-average shares outstanding, as they are anti-dilutive, are as follows: ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, ​ ​ 2024 ​ 2023 Common stock warrants — 145,600 Common stock options 6,589,116 4,494,994 Restricted stock units 902,952 ​ 629,793 ​ ​ ​ 10. Commitments and Contingencies Spitfire Acquisition In July 2019, the Company entered into the Spitfire merger agreement to acquire all of the equity interests of Spitfire Pharma, Inc. (“Spitfire”). Spitfire was a privately held, preclinical pharmaceutical company developing novel peptide products for pharmaceutical indications, including pemvidutide for the treatment of MASH. As part of the agreement, the Company is obligated to make payments of up to $ 80.0 million upon the achievement of specified worldwide net sales of all products developed using the technology acquired from Spitfire Pharma Inc. (the “Sales Milestone”) within ten years following the approval of a new drug application filed with the U.S. Food and Drug Administration (the “FDA”). Litigation On May 6, 2024, a class action complaint was filed in federal district court in the District of Maryland, Southern Division, naming as defendants, the Company and three of the Company’s current executive officers, captioned Mogan v. Altimmune, Inc., et al., No. 24-cv-01315 (D. Md.). The complaint alleges that the defendants violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, and Rule 10b-5 thereunder, by making false and misleading 11 Table of Contents statements and omissions of material fact to the investing public including the plaintiff and class members, who purchased or otherwise acquired the Company’s common stock between December 1, 2023 and April 26, 2024. The plaintiff and class members seek to have the action maintained as a class action under Rule 23 of the Federal Rules of Civil Procedure and for the defendants to pay damages, interest, and an award of costs, including attorneys’ fees. The Company intends to vigorously defend against the lawsuit. The Company is a party in various contracts and subject to disputes, litigation, and potential claims arising in the ordinary course of business none of which are currently reasonably possible or probable of material loss. ​ ​ ​ 12 Table of Contents