Q - SIGA TECHNOLOGIES

3. Procurement Contracts and Research Agreements

19C BARDA Contract

On* September 10, 2018,the Company entered into a contract with the U.S. Biomedical Advanced Research and Development Authority ("BARDA") pursuant to which SIGA agreed to deliver up to 1,488,000 courses of oral TPOXX® to the U.S. Strategic National Stockpile ("Strategic Stockpile"), and to manufacture and deliver to the Strategic Stockpile, or store as vendor-managed inventory, up to 212,000 courses of IV TPOXX®. In October 2023,the contract was modified so that a course of IV TPOXX® was redefined within the contract from being 14 vials to being 28 vials; as such, the19C* BARDA Contract currently specifies 106,000 courses of IV TPOXX® (for the same payment amount as originally specified). In addition to the delivery of TPOXX® courses, the contract includes funding from BARDA for a range of activities, including: advanced development of IV TPOXX®, post-marketing activities for oral and IV TPOXX®, development of a pediatric formulation, and procurement activities. On* April 8, 2025,total payments contemplated under the contract with BARDA were increased by $14.3 million to add funding for activities supporting manufacturing. On June 3, 2025,total payments contemplated under the contract with BARDA were increased by $13.2 million in connection with the development of the pediatric formulation of TPOXX®. As of June 30, 2025*, the contract with BARDA (as amended, modified, or supplemented from time to time, the*"19C* BARDA Contract") contemplates up to approximately $630 million of payments, of which approximately $79.2 million of payments are included within the base period of performance, approximately $545.2 million of payments are related to exercised options, and up to approximately $5.6 million of payments are currently specified as unexercised options. BARDA* maychoose in its sole discretion when, or whether, to exercise any of the unexercised options. The period of performance for options is up toten years from the date of entry into the19C* BARDA Contract and such options could be exercised at any time during the contract term.

The base period of performance specifies potential payments of approximately $79.2 million for the following activities: payments of approximately $11.1 million for the delivery of approximately 35,700 courses of oral TPOXX® to the Strategic Stockpile; payments of $8.0 million for the manufacture of 10,000 courses (as currently defined within the contract as being28 vials) of final drug product of IV TPOXX® ("IV FDP"), of which $3.2 million of payments are related to the manufacture of bulk drug substance ("IV BDS") to be used in the manufacture of IV FDP; payments of approximately $59.5 million to fund reimbursed activities; and payments of approximately $0.6 million for supportive procurement activities. As of* June 30, 2025*, the Company had received $11.1 million for the delivery of approximately 35,700 courses of oral TPOXX® to the Strategic Stockpile, $3.2 million for the manufacture of IV BDS, $4.8 million for the delivery of IV FDP to the Strategic Stockpile and $27.6 million for other base period activities. IV BDS has been used for the manufacture of courses of IV FDP. The $3.2 million received for the completed manufacture of IV BDS had been recorded as deferred revenue as of* December 31, 2021,but with the delivery of IV FDP to the Strategic Stockpile during2022,* $2.9 million was recognized as revenue. The remaining $0.3 million of deferred revenue was recognized in thesecond quarter of2024 as the IV FDP containing such IV BDS was delivered to and accepted by the Strategic Stockpile.

The options that have been exercised as of* June 30, 2025*, provide for payments up to approximately $545.2 million. As of* June 30, 2025*, there are exercised options for the following activities: payments up to $450.2 million for the manufacture and delivery of up to 1.5 million courses of oral TPOXX®; payments up to $76.8 million for the manufacture of courses of IV FDP; payments of up to approximately $3.6 million to fund post-marketing activities for IV TPOXX®; and payments of up to $14.6 million for funding of post-marketing activities for oral TPOXX®. As of* June 30, 2025*, a cumulative total of $450.2 millionof oral TPOXX® has been delivered to the Strategic Stockpile and accepted; a cumulative total of $61.4 million of IV BDS or IV FDPhas been either set aside in inventory or delivered to the Strategic Stockpile and accepted (IV BDS that has been set aside has been recorded as deferred revenue and will be recognized as revenue when the IV BDS is manufactured as IV FDP and delivered); and the Company has been cumulatively reimbursed $10.4 million in connection with post-marketing activities for oral and IV TPOXX®.

Unexercised options, as of* June 30, 2025*, specify potential payments up to approximately $5.6 million in total (if all such options are exercised), of which approximately $5.6 million relates to supportive activities that we currently donot expect to be required.

6

The options related to IV TPOXX® were divided intotwo primary manufacturing steps. There were options related to the manufacture of bulk drug substance (“IV BDS Options”), and there were corresponding options (for the same number of IV courses) for the manufacture of final drug product (“IV FDP Options”). BARDA had the sole discretion to choose to exercise any, all, ornone of these options. The19C BARDA Contract included: three separate IV BDS Options, each providing for the bulk drug substance equivalent of 32,000 courses (as currently defined within the contract) of IV TPOXX®; andthree separate IV FDP Options, each providing for 32,000 courses of final drug product of IV TPOXX®. BARDA had the sole discretion as to whether to simultaneously exercise IV BDS Options and IV FDP Options, or whether to exercise options at different points in time (or alternatively, to only exercise the IV BDS Option butnot the IV FDP Option). To date, BARDA has exercised allthree IV BDS options and allthree IV FDP options.

Revenues in connection with the19C BARDA Contract are recognized either over time or at a point in time. Performance obligations related to product delivery generate revenue at a point in time. Revenue from other performance obligations under the19C BARDA Contract are recognized over time using an input method using costs incurred to date relative to total estimated costs at completion. For thethree months ended* June 30, 2025and2024*, the Company recognized revenues of $2.0 million and $1.1 million, respectively, on an over time basis. For thesix months ended* June 30, 2025and2024*, the Company recognized revenues of $3.2 million and $2.7 million, respectively, on an over time basis. In contrast, revenue recognized for product delivery, and therefore at a point in time, for each of thethree andsix months ended* June 30, 2025* was $79.1 million. Revenue recognized for product delivery, and therefore at a point in time, for thethree andsix months ended* June 30, 2024* was $17.6 million and $32.3 million, respectively.

U.S. Department of Defense Procurement Contracts

In2024, the Company had sales of approximately $10 million to the U.S. Department of Defense ("DoD") of which $1.1 million was delivered and recognized during thesix months ended* June 30, 2024*. Sales consisted mostly of delivery of oral TPOXX®, with a minor amount of IV TPOXX® delivered.

International Sales Activity

In thesix months ended* June 30, 2025*, the Company had international sales of $5.8 million, consisting of a delivery of oral TPOXX® toone country. In thethree andsix months ended* June 30, 2024*, the Company had international sales of $3.0 million and $11.0 million, respectively. International sales in thesix months ended* June 30, 2024*, were made under the International Promotion Agreement (defined and discussed below) with Meridian Medical Technologies, LLC ("Meridian"). Through the International Promotion Agreement, Meridian was the counterparty to the international contracts under which sales were made during thesix months ended* June 30, 2024*.

Revenue in connection with international procurement contracts for the delivery of product are recognized at a point in time on a gross basis, as the Company acts as the principal in the transaction. During thesix months ended* June 30, 2025*, the Company recognized $5.8 million of sales in connection with international contracts. There wasno revenue recognized in connection with international contracts during thethree months ended* June 30, 2025*. During thethree andsix months ended* June 30, 2024*, the Company recognized $3.0 million and $11.0 million of sales, respectively, in connection with international contracts.

7

International Promotion Agreement

Under the terms of the current International Promotion Agreement, which was amended on* March 27, 2024,and effective June 1, 2024,and further amended on August 30, 2024,the Company has primary responsibility for the advertising, promotion and sale of oral TPOXX® in all geographic regions. Meridian has limited, non-exclusive rights to advertise, promote, offer for sale and sell oral TPOXX® in the European Economic Area, Australia, Japan, Switzerland, the United Kingdom and the Association of Southeast Asian Nations and its member states (collectively, the “Current Territory”). Meridian also performs non-promotional activities under specified contracts withthird* parties entered into prior to* June 1, 2024,that provide for the sale of oral TPOXX® in the Current Territory. The International Promotion Agreement entitles Meridian to receive a fee equal to a high single digit percentage of collected proceeds (whether collected by Meridian or the Company), net of certain expenses, of sales of oral TPOXX® in the Current Territory in the field of use specified in the International Promotion Agreement. The International Promotion Agreement has a fixed term that expires on May 31, 2026,withno* automatic renewal.

Under the terms of the original International Promotion Agreement (“Pre-amendment International Promotion Agreement”), which had an initial term that expired on* May 31, 2024,Meridian had been granted exclusive rights to market, advertise, promote, offer for sale, or sell oral TPOXX® in a field of use specified in the International Promotion Agreement in all geographic regions except for the United States (the “Territory”), and Meridian agreednot* to commercialize any competing product, as defined in the Pre-amendment International Promotion Agreement, in the specified field of use in the Territory. Under the Pre-amendment International Promotion Agreement, as well as the current International Promotion Agreement, SIGA has always retained ownership, intellectual property, distribution and supply rights and regulatory responsibilities in connection with TPOXX®, and, in the United States market, also retained sales and marketing rights with respect to oral TPOXX®. SIGA’s consent is required prior to the entry by Meridian into any sales arrangement pursuant to the International Promotion Agreement.

Sales to international customers pursuant to the Pre-amendment International Promotion Agreement were invoiced and collected by Meridian, and such collections were remitted, less Meridian’s fees, to the Company under a quarterly process specified in the Pre-amendment International Promotion Agreement; and Meridian was entitled to a specified percentage of the collected proceeds of sales of oral TPOXX®, net of certain expenses, for calendar years in which customer collected amounts net of such expenses were less than or equal to a specified threshold, and to a higher specified percentage of such collected net proceeds for calendar years in which such net collected amounts exceeded the specified threshold. Subsequent to* June 1, 2024,only specified procurement contracts for the Current Territory entered into prior to June 1, 2024,*continue to involve Meridian invoicing and collecting proceeds, and retaining a fee pursuant to the International Promotion Agreement.

8

4. Inventory

Inventory includes costs related to the manufacture of TPOXX®. Inventory consisted of the following:

During thethree months ended* June 30, 2025*, the Company wrote off approximately $0.9 million of inventory. In addition, during thesix months ended* June 30, 2025*, the Company recognized a recovery of approximately $0.5 million from a contract manufacturing organization associated with a previous loss of inventory.

5. Property, Plant and Equipment

Property, plant and equipment consisted of the following:

Depreciation and amortization expense on property, plant, and equipment was $0.3 million for each of thesix months ended* June 30, 2025and2024*.

6. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following:

9

7. Fair Value of Financial Instruments

The carrying value of cash and cash equivalents, accounts receivable, accounts payable, accrued expenses and other current liabilities, and income tax payable approximates fair value due to the relatively short maturity of these instruments.

The measurement of fair value requires the use of techniques based on observable and unobservable inputs. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect our market assumptions. The inputs create the following fair value hierarchy:

There wereno transfers between levels of the fair value hierarchy for thesix months ended* June 30, 2025*. As of* June 30, 2025* and* December 31, 2024*, the Company had $54.7 million and $53.5 million, respectively, of cash equivalents classified as Level1 financial instruments. There wereno Level2 or Level3 financial instruments as of* June 30, 2025* or* December 31, 2024*.

8. Per Share Data

The Company computes, presents and discloses earnings per share in accordance with the authoritative guidance, which specifies the computation, presentation and disclosure requirements for earnings per share of entities with publicly held common stock or potential common stock. The objective of basic EPS is to measure the performance of an entity over the reporting period by dividing income by the weighted average shares outstanding. The objective of diluted EPS is consistent with that of basic EPS, except that it also gives effect to all potentially dilutive common shares outstanding during the period.

The following is a reconciliation of the basic and diluted earnings per share computation:

For thethree andsix months ended* June 30, 2025* and2024, weighted-average diluted shares include the dilutive effect of in-the-money options and stock-settled RSUs. The dilutive effect of stock-settled RSUs and options is calculated based on the average share price for each fiscal period using the treasury stock method. Under the treasury stock method, the amount the employee must pay for exercising stock options, the average amount of compensation cost for future service that the Company hasnot yet recognized, and the amount of tax benefits that would be recorded in additional paid-in capital when the award becomes deductible, are collectively assumed to be used to repurchase shares. Cash-settled RSUs were presumed to be cash-settled and therefore excluded from the diluted earnings per share calculations for thethree andsix months ended* June 30, 2025* and2024 because the net effect of their inclusion, including the elimination of the impact in the operating results of the change in fair value of these RSUs, would have been anti-dilutive. Performance-based RSUs were excluded from the diluted earnings per share calculations for thethree andsix months ended* June 30, 2025,as a result of the associated metrics/contingenciesnot* being achieved. For thethree andsix months ended* June 30, 2025*, the weighted average number of shares under the cash-settled RSUs and performance-based RSUs excluded from the calculation of diluted earnings per share was 305,439 and 255,628, respectively. For thethree andsix months ended* June 30, 2024*, the weighted average number of shares under the cash-settled RSUs excluded from the calculation of diluted earnings per share was 55,295 and 57,303, respectively.

10

9. Commitments and Contingencies

From time to time, we* maybe involved in a variety of claims, suits, investigations and proceedings arising from the ordinary course of our business, collections claims, breach of contract claims, labor and employment claims, tax and other matters. Although such claims, suits, investigations and proceedings are inherently uncertain and their results cannot be predicted with certainty, we believe that the resolution of such current pending matters, if any, willnot* have a material adverse effect on our business, consolidated financial position, results of operations or cash flow. Regardless of the outcome, litigation can have an adverse impact on us because of legal costs, diversion of management resources and other factors.

Purchase Commitments

In the course of our business, the Company regularly enters into agreements withthird party organizations to provide contract manufacturing services and research and development services. Under these agreements, the Company issues purchase orders, which obligate the Company to pay a specified price when agreed-upon services are performed. In connection with many CMO purchase orders, reimbursement by CMOs for inventory losses is limited. Commitments under the purchase orders donot exceed our planned commercial and research and development needs. As of* June 30, 2025*, the Company had approximately $19.3 million of purchase commitments associated with manufacturing obligations.

10. Related Party Transactions

Real Estate Leases

On* May 26, 2017,the Company and MacAndrews & Forbes Incorporated ("M&F") entered into aten*-year Office Lease agreement (the "New HQ Lease"), pursuant to which the Company agreed to lease 3,200 square feet at31 East62nd Street, New York, New York. The Company is utilizing premises leased under the New HQ Lease as its corporate headquarters. The Company's rental obligations consisted of a fixed rent of $25,333 per month in thefirst sixty-three months of the term, subject to a rent abatement for thefirst six months of the term. From thefirst day of thesixty-fourth month of the term through the expiration or earlier termination of the lease, the Company's rental obligations consist of a fixed rent of $29,333 per month. In addition to the fixed rent, the Company will pay a facility fee in consideration of the landlord making available certain ancillary services, commencing on thefirst anniversary of entry into the lease. The facility fee was $3,333 per month for thesecond year of the term and increases byfive percent each year thereafter, to $4,925 per month in the final year of the term. During thethree andsix months ended* June 30, 2025*, the Company paid $0.1 million and $0.2 million, respectively, for rent and ancillary services associated with this lease. The Company hadno outstanding payables or accrued expenses related to this lease as of* June 30, 2025*.

Board of Directors and Outside Consultant

Effective* June 13, 2023,an individual was elected to the Company's Board of Directors who was already providing and continued to provide consulting services to the Company. Under a consulting agreement, the director received a monthly fee of $20,000 in2023* and2024. During thetwo months ended* February 28, 2025,the Company incurred $40,000 under this agreement prior to the individual's resignation from the Company's Board of Directors on March 6, 2025.As of June 30, 2025*, the Company hadno outstanding payables or accrued expenses related to the services performed by this vendor through* March 6, 2025.*

11

11. Segment and Geographic Information

The Company operates inone single operating and reportable segment, which includes all activities related to the sale of the Company’s oral and IV TPOXX® as well as research and development services. The Company derives revenue primarily from sales to the U.S. Government as well as international governments (including government affiliated entities) and manages the business activities on a consolidated basis. The segment derives revenues from customers through the delivery of product and fulfillment of research and development services.

The Chief Operating Decision Maker ("CODM") assesses performance for the segment and decides how to allocate resources based on net income that also is reported on the income statement as consolidated net income. Consolidated net income is also a measure that is considered in monitoring budget versus actual results.

The CODM doesnot review assets in evaluating the results of the segment, and therefore, such information isnot presented.

The following table provides the operating result of the Company's segment:

(1) Other segment items include insurance, regulatory and consultant expenses, as well as various general corporate costs.

Revenues by geographic region were as follows:

12

12. Income Taxes

The Company’s provision for income taxes consists of federal and state taxes, as applicable, in amounts necessary to align the Company’s year-to-date tax provision with the effective rate that it expects to achieve for the full year. Each quarter the Company updates its estimate of the annual effective tax rate and records cumulative adjustments as necessary.

For thethree months ended* June 30, 2025and2024*, we recorded pre-tax income of $47.3 million and $2.4 million, respectively, and a corresponding income tax provision of $11.8 million and $0.6 million, respectively.

For thesix months ended* June 30, 2025and2024*, we recorded pre-tax income of $46.7 million and $15.6 million, respectively, and a corresponding income tax provision of $11.6 million and $3.5 million, respectively.

The effective tax rate for thethree months ended* June 30, 2025* was 24.9% compared to 23.6% for thethree months ended* June 30, 2024*. The effective tax rate for thethree months ended* June 30, 2025* differs from the U.S. statutory rate of 21% primarily as a result of state taxes, and various non-deductible expenses, including executive compensation under Internal Revenue Code Section162(m).

The effective tax rate for thesix months ended* June 30, 2025* was 24.9% compared to 22.4% for thesix months ended* June 30, 2024*. The effective tax rate for thesix months ended* June 30, 2025* differs from the U.S. statutory rate of 21% primarily as a result of state taxes, and various non-deductible expenses, including executive compensation under Internal Revenue Code Section162(m).

The Inflation Reduction Act of2022 (the “Act”) was signed into U.S. law on* August 16, 2022.The Act includes various tax provisions, including an excise tax on stock repurchases, expanded tax credits for clean energy incentives, and a corporate alternative minimum tax that generally applies to U.S. corporations with average adjusted annual financial statement income over athree*-year period in excess of*$1* billion. The Company doesnot expect the Act to materially impact its consolidated financial statements.

Effective beginning in fiscal2022, the U.S. Tax Cuts and Job Act of2017 ("TCJA") requires the Company to deduct U.S. and international research and development expenditures ("R&D") for tax purposes over5 to15 years, instead of in the current fiscal year. The Company concurrently records a deferred tax benefit for the future amortization of the research and development for tax purposes. The requirement to expense R&D as incurred is unchanged for U.S. GAAP purposes and the impact to pre-tax R&D expense isnot affected by this provision.

On* July 4, 2025,President Trump signed H.R.1, the “One Big Beautiful Bill Act”, into law. In accordance with U.S. GAAP, the Company will account for the tax effects of changes in tax law in the period of enactment which is thethird* quarter of calendar year2025. The Company is currently in the process of analyzing the tax impacts of the law change, but we donot expect a material impact to the Company's effective tax rate.

13

13. Equity

The tables below present changes in stockholders' equity for thethree andsix months ended* June 30, 2025* and2024.

On* April 8, 2025,the Board of Directors declared a special dividend of $0.60 per share on the common stock of the Company, which resulted in an overall dividend payment of approximately $43 million. The special dividend was paid on May15,* 2025** to shareholders of record at the close of business on* April 29, 2025.*

14

14. Leases

The Company leases its Corvallis, Oregon, office space under an operating lease, which was signed on* November 3, 2017and commenced on January 1, 2018.The initial term of this lease was to expire on December 31, 2019after which the Company hadtwo successive renewal options;one fortwo years and the other forthree years. In thesecond* quarter of2019, the Company exercised thefirst renewal option, which extended the lease expiration date to* December 31, 2021.In thesecond* quarter of2021, the Company exercised thesecond renewal option, which extended the lease expiration date to* December 31, 2024.In thesecond* quarter of2024, the Company entered into an additional addendum, which extended the lease expiration date to* December 31, 2026.In connection with this additional addendum, the Company recorded an increase to operating lease right-of-use assets and operating lease liabilities of approximately $0.5 million in thesecond* quarter of2024.

On* May 26, 2017,the Company and M&F entered into the New HQ Lease, aten-year office lease agreement, pursuant to which the Company agreed to lease 3,200 square feet in New York, New York. The Company is utilizing premises leased under the New HQ Lease as its corporate headquarters. The Company hasno* leases that qualify as finance leases.

Operating lease costs totaled $0.2 million for each of thethree months ended* June 30, 2025and2024*. Operating lease costs totaled $0.3 million for each of thesix months ended* June 30, 2025and2024*. Cash paid for amounts included in the measurement of lease liabilities from operating cash flows was $0.2 million for each of thethree months ended* June 30, 2025and2024*. Cash paid for amounts included in the measurement of lease liabilities from operating cash flows was $0.3 million for each of thesix months ended* June 30, 2025and2024*. As of* June 30, 2025*, the weighted-average remaining lease term of the Company’s operating leases was 1.73 years while the weighted-average discount rate was 9.95%.

Future cash flows under operating leases as of* June 30, 2025* are expected to be as follows:

As of* June 30, 2025*, approximately $0.5 million of the lease liability is included in Other liabilities on the condensed consolidated balance sheet with the current portion included in accrued expenses.

15