# EDGAR Filing Document

**Accession Number:** 0001010086
**File Stem:** 0001140361-26-026380
**Filing Date:** 2026-6
**Character Count:** 33898
**Document Hash:** 7d6e8455894c9eb7609de0b2b161544a
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001140361-26-026380.hdr.sgml**: 20260625

**ACCESSION NUMBER**: 0001140361-26-026380

**CONFORMED SUBMISSION TYPE**: S-8

**PUBLIC DOCUMENT COUNT**: 13

**FILED AS OF DATE**: 20260625

**DATE AS OF CHANGE**: 20260625

**EFFECTIVENESS DATE**: 20260625

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** SIGA TECHNOLOGIES INC
- **CENTRAL INDEX KEY:** 0001010086
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 133864870
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** S-8
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-297025
- **FILM NUMBER:** 261121923

**BUSINESS ADDRESS:**
- **STREET 1:** 31 EAST 62ND STREET
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10065
- **BUSINESS PHONE:** 212-672-9100

**MAIL ADDRESS:**
- **STREET 1:** 31 EAST 62ND STREET
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10065

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** SIGA PHARMACEUTICALS INC
- **DATE OF NAME CHANGE:** 19961108

**As filed with the Securities and Exchange Commission on June 25, 2026.**

**Registration No. 333-**

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**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

**Washington, D.C. 20549**

------

**FORM S-8**

**REGISTRATION STATEMENT**

**UNDER** 

**THE SECURITIES ACT OF 1933**

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## SIGA Technologies, Inc.
(Exact name of Registrant as specified in its charter)

------

---

| | |
|:---|:---|
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **Delaware**  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **13-3864870**  |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; (State or other jurisdiction of incorporation or organization)  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; (I.R.S. Employer Identification No.)  |

---

**31 East 62nd Street**

**New York, NY 10065**

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **(212) 672-9100**

(Address of principal executive offices) (Zip code)

**SIGA Technologies, Inc. Amended and Restated 2010 Stock Incentive Plan**

**(as amended, effective June 9, 2026)**

(Full titles of the plans)

**Daniel J. Luckshire**

**Executive Vice President and Chief Financial Officer**

**31 East 62nd Street**

**New York, NY 10065**

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; **(212) 672-9100**

(Name and address of agent for service) (Telephone number, including area code, of agent for service)

Copies to:

**Peter D. Serating**

**Skadden, Arps, Slate, Meagher & Flom LLP**

**One Manhattan West**

**New York, NY 10001**

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(212) 735-3000**

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.

---

| | | | |
|:---|:---|:---|:---|
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Large accelerated filer  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ☐  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Accelerated filer  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ☒  |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Non-accelerated filer  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ☐  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Smaller reporting company  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ☐  |
|  |  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Emerging growth company  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ☐  |

---

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

------

**REGISTRATION OF ADDITIONAL SHARES**

**PURSUANT TO GENERAL INSTRUCTION E**

Pursuant to General Instruction E of Form S-8, SIGA Technologies, Inc. (the "***Registrant***") is filing this Registration Statement with the Securities and Exchange Commission (the "***Commission***") to register 6,500,000 additional shares of its common stock, par value $0.0001 per share (the "***Common Stock***"), issuable under the Registrant's Amended and Restated 2010 Stock Incentive Plan (as amended, the "***2010 Plan***"). At the Registrant's 2026 Annual Meeting of Stockholders held on June 9, 2026, the Registrant's stockholders approved an amendment to the 2010 Plan to authorize an additional 6,500,000 shares of Common Stock for issuance under the 2010 Plan. In accordance with the instructional note to Part I of Form S-8 as promulgated by the Commission, the information specified by Part I of the Form S-8 has been omitted from this Registration Statement.

These shares of Common Stock are additional securities of the same class as other securities for which the Registration Statements on Form S-8 were previously filed with the Commission (File Nos. [333-218507](https://www.sec.gov/Archives/edgar/data/1010086/000114036117023791/forms8.htm), [333-183101](https://www.sec.gov/Archives/edgar/data/1010086/000114036112035335/kl07022.htm), and [333-167329](https://www.sec.gov/Archives/edgar/data/1010086/000092242310000275/kl06005.htm)) (collectively, the "***Prior Registration Statements***"). Pursuant to General Instruction E to Form S-8, the contents of the Prior Registration Statements are incorporated by reference into this Registration Statement, except that the provisions contained in Part II of such Prior Registration Statements are modified or supplemented, as the case may be, as set forth in this Registration Statement.

**PART II**

**Item 6.**

**Indemnification of Directors and Officers.**

The Registrant's Amended and Restated Certificate of Incorporation (the "***Certificate of Incorporation***") at Article Seventh provides that no director or officer of the Registrant shall be personally liable to the Registrant or its stockholders for monetary damages for breach of fiduciary duty as a director or officer, provided, however, that this provision shall not eliminate or limit the liability of a director or officer (i) for any breach of the director's or officer's duty of loyalty to the Registrant or its stockholders, (ii) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (iii) under Section 174 of the General Corporation Law of Delaware ("***DGCL***"), or (iv) from any transaction from which the director or officer derived an improper personal benefit. Article Eighth of the Certificate of Incorporation provides that the Registrant shall indemnify, in accordance with and to the fullest extent now or hereafter permitted by law, any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (including, without limitation, an action by or in the right of the Registrant), by reason of his acting as a director of the Registrant (and the Registrant, in the discretion of the Board, may so indemnify a person by reason of the fact that he is or was an officer of the Registrant) against any liability or expense actually and reasonably incurred by such person in respect thereof; provided, however, that, the Registrant shall not be obligated to indemnify any such person (i) with respect to proceedings, claims or actions initiated or brought voluntarily by such person and not by way of defense, or (ii) for any amounts paid in settlement of an action effected without the prior written consent of the Registrant to such settlement. Such indemnification is not exclusive of any other right to indemnification provided by law, agreement or otherwise. Article Ninth of the Certificate of Incorporation provides that no amendment to or repeal of Article Seventh or Article Eighth of the Certificate of Incorporation shall apply to or have any effect on the rights of any individual referred to in Article Seventh or Article Eighth for or with respect to acts or omissions of such individual occurring prior to such amendment or repeal.

------

The Registrant's Amended and Restated Bylaws at Article VII provide that each person who was or is made a party or is threatened to be made a party to or is involved in or called as a witness in any proceeding because he or she is a person who is, was, or had agreed to become a director or an officer of the Registrant, shall be indemnified and held harmless by the Registrant to the fullest extent permitted under the DGCL, as the same now exists or may hereafter be amended (but, in the case of any such amendment, only to the extent that such amendment permits the Registrant to provide broader indemnification rights than the DGCL permitted the Registrant to provide prior to such amendment). Such indemnification shall cover all expenses incurred by such indemnified person (including, but not limited to, attorneys' fees and other expenses of litigation) and all liabilities and losses (including, but not limited to, judgments, fines, ERISA or other excise taxes or penalties and amounts paid or to be paid in settlement) incurred by such person in connection therewith. Notwithstanding the preceding sentence, the Registrant shall be required to indemnify a person in connection with a proceeding initiated by such person only if the proceeding was authorized by the Board of Directors of the Registrant.

The Registrant shall pay the expenses (including attorneys' fees) incurred in defending or otherwise being involved in a proceeding in advance of its final disposition, including any appeal therefrom, upon receipt of an undertaking by or on behalf of such person to repay such amount if it shall ultimately be determined that he or she is not entitled to be indemnified by the Registrant; provided, that in connection with a proceeding (or part thereof) initiated by such person, the Registrant shall pay said expenses in advance of final disposition only if such proceeding (or part thereof) was authorized by the Board of Directors. A person to whom expenses are advanced pursuant hereto shall not be obligated to repay pursuant to the undertaking until the final determination of any pending proceeding in a court of competent jurisdiction concerning the right of such person to be indemnified or the obligation of such person to repay pursuant to the undertaking.

If a claim for indemnification is not promptly paid in full by the Registrant after a written claim has been received by the Registrant or if expenses have not been promptly advanced after a written request for such advancement accompanied by the undertaking has been received by the Registrant, the claimant may at any time thereafter bring suit against the Registrant to recover the unpaid amount of the claim or the advancement of expenses. If successful, in whole or in part, in such suit, such claimant shall also be entitled to be paid the reasonable expense thereof. It shall be a defense to any such action (other than an action brought to enforce a claim for expenses incurred in defending any proceeding in advance of its final disposition where the required undertaking has been tendered to the Registrant) that indemnification of the claimant is prohibited by law, but the burden of proving such defense shall be on the Registrant. Neither the failure of the Registrant (including its Board of Directors, independent legal counsel, or its stockholders) to have made a determination, if required, prior to the commencement of such action that indemnification of the claimant is proper in the circumstances, nor an actual determination by the Registrant (including its Board of Directors, independent legal counsel, or its stockholders) that indemnification of the claimant is prohibited, shall be a defense to the action or create a presumption that indemnification of the claimant is prohibited.

The rights conferred on any person pursuant to Article VII of the Amended and Restated Bylaws of the Registrant shall not be exclusive of any other rights which such person may have or hereafter acquire under any statute, provision of the Certificate of Incorporation, by-law, agreement, vote of stockholders or disinterested directors or otherwise. The Board of Directors shall have the authority, by resolution, to provide for such other indemnification of directors or officers of the Registrant as it shall deem appropriate.

------

The Registrant may maintain insurance, at its expense, to protect itself and any director or officer against any expenses, liabilities or losses, whether or not the Registrant would have the power to indemnify such person against such expenses, liabilities or losses under the DGCL. The Registrant may enter into contracts with any director or officer of the Registrant in furtherance of the provisions of Article VII of the Amended and Restated Bylaws and may create a trust fund, grant a security interest or use other means (including, without limitation, a letter of credit) to ensure the payment of such amounts as may be necessary to effect the advancing of expenses and indemnification as provided in Article VII of the Amended and Restated Bylaws.

The provisions of Article VII of the Amended and Restated Bylaws shall be applicable to all proceedings commenced or continuing after its adoption, whether such arise out of events, acts or omissions which occurred prior or subsequent to such adoption, and shall continue as to a person who has ceased to be a director or officer and shall inure to the benefit of the heirs, executors and administrators of such person. Article VII of the Amended and Restated Bylaws shall be deemed to be a contract between the Registrant and each person who, at any time that Article VII is in effect, serves or agrees to serve in any capacity which entitles him or her to indemnification thereunder and any repeal or other modification of Article VII of the Amended and Restated Bylaws or any repeal or modification of the DGCL or any other applicable law shall not limit any indemnified person's entitlement to the advancement of expenses or indemnification under Article VII of the Amended and Restated Bylaws for proceedings then existing or later arising out of events, acts or omissions occurring prior to such repeal or modification, including, without limitation, the right to indemnification for proceedings commenced after such repeal or modification to enforce Article VII of the Amended and Restated Bylaws with regard to proceedings arising out of acts, omissions or events occurring prior to such repeal or modification.

The Registrant maintains insurance policies under which the directors and officers of the Registrant are insured, within the limits and subject to the limitations of the policies, against certain expenses in connection with the defense of actions, suits or proceedings, and certain liabilities which might be imposed as a result of such actions, suits or proceedings, to which they are parties by reason of being or having been such directors or officers which could include liabilities under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended.

**Item 8.**

**Exhibits**

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| | |
|:---|:---|
| **Exhibit<br> No.** | **Description** |
| 4.1 | [Amended and Restated Certificate of Incorporation of SIGA Technologies, Inc. (incorporated by reference to Exhibit 3(a) to the Annual Report on Form 10-K of the Company filed on March 10, 2026).](https://www.sec.gov/Archives/edgar/data/1010086/000143774926007557/ex_925381.htm)  |
| 4.2 | [Amended and Restated By-laws of SIGA Technologies, Inc. (incorporated by reference to Exhibit 3.1 to the Current Report on Form 8-K of the Company filed on June 12, 2025).](https://www.sec.gov/Archives/edgar/data/1010086/000114036125022316/ef20050546_ex3-1.htm)  |
| 4.3 | [Form of Common Stock Certificate (incorporated by reference to the Form SB-2 Registration Statement of the Company dated March 10, 1997 (No. 333-23037)).](https://www.sec.gov/Archives/edgar/data/1010086/0000950130-97-000939.txt)  |
| 4.4 | [SIGA Technologies, Inc. 2010 Stock Incentive Plan (amended and restated effective May 23, 2017) (incorporated by reference to Exhibit 10(nn) to the Annual Report on Form 10-K of the Company filed on March 11, 2025).](https://www.sec.gov/Archives/edgar/data/1010086/000143774925007056/ex_778098.htm)  |
| 4.5 | [Amendment to the SIGA Technologies, Inc. 2010 Stock Incentive Plan, effective June 9, 2026 (incorporated by reference to Exhibit 10.1 to the Current Report on Form 8-K of the Company filed on June 10, 2026).](https://www.sec.gov/Archives/edgar/data/1010086/000114036126024780/ef20075854_ex10-1.htm)  |
| 5.1\* | [Opinion of Skadden, Arps, Slate, Meagher & Flom LLP.](ef20076671_ex5-1.htm)  |
| 23.1\* | [Consent of Skadden, Arps, Slate, Meagher & Flom LLP (contained in Exhibit 5.1).](ef20076671_ex5-1.htm)  |
| 23.2\* | [Consent of PricewaterhouseCoopers LLP, independent registered public accounting firm.](ef20076671_ex23-2.htm)  |
| 24.1\* | [Power of Attorney (included on signature page).](#PowerofAttorney)  |
| 107\* | [Filing Fee Table](ef20076671_ex107.htm)  |

---

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**SIGNATURES**

Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of New York, State of New York, on June 25, 2026.

---

| | |
|:---|:---|
| **SIGA TECHNOLOGIES, INC.** | **SIGA TECHNOLOGIES, INC.** |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; By:  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /s/ Daniel J. Luckshire  |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Name:  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Daniel J. Luckshire  |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Title:  | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Executive Vice President and Chief Financial Officer  |

---

**POWER OF ATTORNEY**

Each person whose signature appears below constitutes and appoints Diem Nguyen, Ph.D., Daniel J. Luckshire and Lawrence Miller, and each one of them, as his or her true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution, for him or her and in their name, place, and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement on Form S-8 to be filed by SIGA Technologies, Inc., and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to be done in and about the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents or their substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons on June 25, 2026 in the capacities indicated.

------

---

| | | |
|:---|:---|:---|
| <u>Signature</u> | <u>Title</u> | <u>Date</u> |
| /s/ Diem Nguyen, Ph.D. | Chief Executive Officer and Director | June 25, 2026 |
| Diem Nguyen, Ph.D. | *(Principal Executive Officer)* |  |
| /s/ Daniel J. Luckshire | Executive Vice President and Chief Financial Officer | June 25, 2026 |
| Daniel J. Luckshire | *(Principal Financial Officer & Principal Accounting Officer)* |  |
| /s/ Jaymie Durnan | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Director  | June 25, 2026 |
| Jaymie Durnan | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Director  | June 25, 2026 |
| /s/ Harold Ford | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Director  | June 25, 2026 |
| Harold Ford | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Director  | June 25, 2026 |
| /s/ Gen. John M. Keane (Ret.) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Director  | June 25, 2026 |
| Gen. John M. Keane (Ret.) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Director  | June 25, 2026 |
| /s/ Joseph W. Marshall, III | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Director  | June 25, 2026 |
| Joseph W. Marshall, III | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Director  | June 25, 2026 |
| /s/ Gary J. Nabel, M.D., Ph.D. | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Director  | June 25, 2026 |
| Gary J. Nabel, M.D., Ph.D. | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Director  | June 25, 2026 |
| /s/ Julian Nemirovsky | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Director  | June 25, 2026 |
| Julian Nemirovsky | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Director  | June 25, 2026 |
| /s/ Holly L. Phillips, M.D. | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Director  | June 25, 2026 |
| Holly L. Phillips, M.D. | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Director  | June 25, 2026 |

---

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## Exhibit 5.1

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#### Exhibit 5.1

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| | |
|:---|:---|
| &nbsp;&nbsp; Skadden, Arps, Slate, Meagher & Flom llp  |  |
| &nbsp;&nbsp; 1440 New York Avenue, N.W.  |  |
| &nbsp;&nbsp; Washington, D.C. 20005  | &nbsp;&nbsp; FIRM/AFFILIATE  |
| &nbsp;&nbsp; ________  | &nbsp;&nbsp; OFFICES  |
|  | &nbsp;&nbsp; -----------  |
| &nbsp;&nbsp; TEL: (202) 371-7000  | &nbsp;&nbsp; BOSTON  |
| &nbsp;&nbsp; FAX: (202) 393-5760  | &nbsp;&nbsp; CHICAGO  |
| &nbsp;&nbsp; www.skadden.com  | &nbsp;&nbsp; HOUSTON  |
|  | &nbsp;&nbsp; LOS ANGELES  |
|  | &nbsp;&nbsp; PALO ALTO  |
|  | &nbsp;&nbsp; WASHINGTON, D.C.  |
|  | &nbsp;&nbsp; WILMINGTON  |
|  | &nbsp;&nbsp; -----------  |
|  | &nbsp;&nbsp; ABU DHABI  |
|  | &nbsp;&nbsp; BEIJING  |
|  | &nbsp;&nbsp; BRUSSELS  |
|  | &nbsp;&nbsp; FRANKFURT  |
| &nbsp;&nbsp; June 25, 2026  | &nbsp;&nbsp; HONG KONG  |
|  | &nbsp;&nbsp; LONDON  |
|  | &nbsp;&nbsp; MUNICH  |
|  | &nbsp;&nbsp; PARIS  |
|  | &nbsp;&nbsp; SÃO PAULO  |
|  | &nbsp;&nbsp; SEOUL  |
|  | &nbsp;&nbsp; SINGAPORE  |
|  | &nbsp;&nbsp; TOKYO  |
|  | &nbsp;&nbsp; TORONTO  |

---

SIGA Technologies, Inc.

31 East 62nd Street

New York, NY 10065

(212) 672-9100

Re:

SIGA Technologies, Inc.

<u>Registration Statement on Form S-8</u>

Ladies and Gentlemen:

We have acted as special United States counsel to SIGA Technologies, Inc., a Delaware corporation (the "<u>Company</u>"), in connection with the Company's Registration Statement on Form S-8 (together with the exhibits thereto, the "<u>Registration Statement</u>") to be filed on the date hereof with the Securities and Exchange Commission (the "<u>Commission</u>") under the Securities Act of 1933 (the "<u>Securities Act</u>"), relating to the registration of 6,500,000 additional shares of the Company's Common Stock, par value $0.0001 per share (the "<u>Common Stock</u>"), available for issuance under the Company's Amended and Restated 2010 Stock Incentive Plan (as amended, the "<u>2010 Plan</u>," and such shares, the "<u>Shares</u>").

This opinion letter is being furnished in accordance with the requirements of Item 601(b)(5) of Regulation S-K under the Securities Act.

------

SIGA Technologies, Inc.

June 25, 2026

In rendering the opinion stated herein, we have examined and relied upon the following:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;

(a) the Registration Statement in the form to be filed with the Commission on the date hereof;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;

(b) a copy of the 2010 Plan, certified pursuant to the Secretary's Certificate (as defined below);

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;

(c) an executed copy of a certificate of Lawrence Miller, Secretary of the Company, dated the date hereof (the "<u>Secretary's Certificate</u>");

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;

(d) copies of the Company's Amended and Restated Certificate of Incorporation, as amended (the "<u>Certificate of Incorporation</u>"), certified by the Secretary of State of the State of Delaware as of June 25, 2026, and certified pursuant to the Secretary's Certificate as being in effect on the date of the resolutions referred to below and as of the date hereof;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;

(e) copies of the Company's Amended and Restated Bylaws, as amended (the "<u>Bylaws</u>") certified pursuant to the Secretary's Certificate as being in effect on the date of the resolutions referred to below and as of the date hereof; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;

(f) copies of certain resolutions of the Board of Directors of the Company relating to the approval of the 2010 Plan, including the amendment to the 2010 Plan, effective June 9, 2026, and certain related matters and certified pursuant to the Secretary's Certificate.

We have also examined originals or copies, certified or otherwise identified to our satisfaction, of such records of the Company and such agreements, certificates and receipts of public officials, certificates of officers or other representatives of the Company and others, and such other documents as we have deemed necessary or appropriate as a basis for the opinion stated below.

In our examination, we have assumed the genuineness of all signatures, including electronic signatures, the legal capacity and competency of all natural persons, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as facsimile, electronic, certified or photocopied copies, and the authenticity of the originals of such copies. In making our examination of executed documents, we have assumed that the parties thereto, other than the Company, had the power, corporate or other, to enter into and perform all obligations thereunder and have also assumed the due authorization by all requisite action, corporate or other, and the execution and delivery by such parties of such documents and the validity and binding effect thereof on such parties. As to any facts relevant to the opinion stated herein that we did not independently establish or verify, we have relied upon statements and representations of officers and other representatives of the Company and others and of public officials, including the facts and conclusions set forth in the Certificate of Incorporation and the Secretary's Certificate.

------

SIGA Technologies, Inc.

June 25, 2026

In rendering the opinion set forth below, we have also assumed that (i) the Shares will be issued in book-entry form and an appropriate account statement evidencing the Shares credited to a recipient's account maintained with the Company's transfer agent and registrar will be issued by the Company's transfer agent and registrar, (ii) each award agreement under which options, stock appreciation rights, restricted stock, restricted stock units, stock bonuses, other stock-based awards and certain other awards are granted pursuant to the 2010 Plan will be consistent with the 2010 Plan and will be duly authorized, executed and delivered by the parties thereto, and (iii) the Company's issuance of the Shares does not and will not (a) except to the extent expressly stated in the opinions contained herein, violate any statute to which the Company or such issuance is subject, or (b) constitute a violation of, or a breach under, or require the consent or approval of any other person under, any agreement or instrument binding on the Company (except that we do not make this assumption with respect to the Certificate of Incorporation and the Bylaws although we have assumed compliance with any covenant, restriction or provision with respect to financial ratios or tests or any aspect of the financial condition or results of operations of the Company contained in such instruments) and that the Company will continue to have sufficient authorized shares of Common Stock, and (iv) the Company's authorized capital stock is as set forth in the Certificate of Incorporation and we have relied solely on the certified copy thereof issued by the Secretary of State of the State of Delaware and have not made any other inquiries or investigations.

We do not express any opinion with respect to the laws of any jurisdiction other than the General Corporation Law of the State of Delaware (the "<u>DGCL</u>").

Based upon the foregoing and subject to the qualifications and assumptions stated herein, we are of the opinion that the Shares have been duly authorized by all requisite corporate action on the part of the Company under the DGCL and, when the Shares are issued to the participants in accordance with the terms and conditions of the 2010 Plan and the applicable award agreement for consideration in an amount at least equal to the par value of such Shares, the Shares will be validly issued, fully paid and nonassessable.

We hereby consent to the filing of this opinion letter with the Commission as an exhibit to the Registration Statement. In giving this consent, we do not thereby admit that we are included in the category of persons whose consent is required under Section 7 of the Securities Act or the General Rules and Regulations under the Securities Act. This opinion letter is expressed as of the date hereof unless otherwise expressly stated, and we disclaim any undertaking to advise you of any subsequent changes in the facts stated or assumed herein or of any subsequent changes in applicable laws.

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| |
|:---|
| &nbsp;&nbsp; Very truly yours,  |
| &nbsp;&nbsp; /s/ Skadden, Arps, Slate, Meagher & Flom LLP  |

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PS

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## Exhibit 23.2

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Exhibit 23.2

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration Statement on Form S-8 of SIGA Technologies, Inc. of our report dated March 10, 2026 relating to the financial statements and the effectiveness of internal control over financial reporting, which appears in SIGA Technologies, Inc.'s Annual Report on Form 10-K for the year ended December 31, 2025.

/s/ PricewaterhouseCoopers LLP

&nbsp;&nbsp;&nbsp;&nbsp; Florham Park, New Jersey

&nbsp;&nbsp;&nbsp;&nbsp; June 25, 2026

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## Ex-Filing

?xml version='1.0' encoding='ASCII'?

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**Exhibit 107**

**CALCULATION OF FILING FEE TABLE**

**Form S-8**

(Form Type)

**SIGA Technologies, Inc.**

(Exact Name of Registrant as Specified in its Charter)

**<u>Table 1: Newly Registered Securities</u>**

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| | | | | | |
|:---|:---|:---|:---|:---|:---|
| **Security Type** | **Security Class Title** | **Proposed Maximum Offering <br>Price Per Unit** | **Maximum Aggregate<br>Offering Price** | **Fee Rate** | &nbsp;&nbsp; **Amount of Registration Fee** |
| Equity | Common stock, par value $0.0001 per share, Amended and Restated 2010 Stock Incentive Plan, as Amended 457(a)<sup>(2)</sup> 6500000<sup>(3)</sup> | $4.31 | $28015000.00 | 0.0001381 | $3868.87 |
| &nbsp;&nbsp; **Total Offering Amounts** | &nbsp;&nbsp; **Total Offering Amounts** |  | **$**28015000.00 |  | **$**3868.87 |
| **Total Fees Previously Paid** | **Total Fees Previously Paid** |  |  |  |  |
| &nbsp;&nbsp; **Total Fee Offsets** | &nbsp;&nbsp; **Total Fee Offsets** |  |  |  |  |
| &nbsp;&nbsp; **Net Fee Due** | &nbsp;&nbsp; **Net Fee Due** |  |  |  | **$**3868.87 |

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(1) Pursuant to Rule 416(a)
promulgated under the Securities Act of 1933, as amended (the "  ***Securities Act*** "), this Registration Statement shall also cover any additional
shares of common stock of SIGA Technologies, Inc. (the "  ***Registrant*** ")
that become issuable under the plan set forth herein by reason of any stock
dividend, stock split, recapitalization, or other similar transaction effected
that results in an increase to the number of outstanding shares of Registrant's
common stock, as applicable.

(2) Estimated in accordance
with Rules 457(c) and 457(h) solely for purposes of calculating the
registration fee on the basis of $4.31, the average of the high and low prices
of the Registrant's common stock as reported on the Nasdaq on June 17, 2026.

(3) Represents an additional
6,500,000 shares of the Registrant's common stock reserved for issuance under
the Registrant's Amended and Restated 2010 Stock Incentive Plan, as amended
effective June 9, 2026.

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