[Form 4] SIGA TECHNOLOGIES INC Insider Trading Activity

Rhea-AI Filing Summary

SIGA Technologies Chief Executive Officer Diem Nguyen reported equity compensation activity involving restricted stock units and common shares. On January 27, 2026, 55,902 restricted stock units vested and converted into the same number of common shares at an exercise price of $0 per share.

To cover tax withholding related to this vesting, the issuer withheld 22,804 common shares at $6.82 per share, reducing Nguyen’s directly held common shares to 100,751. Following these transactions, Nguyen also held 55,903 restricted stock units, which continue to vest in equal annual installments over three years from the January 27, 2024 grant date.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Nguyen Diem

(Last) (First) (Middle)

C/O SIGA TECHNOLOGIES, INC.

31 EAST 62ND STREET

(Street)

NEW YORK NY 10065

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
SIGA TECHNOLOGIES INC [ SIGA ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Executive Officer

3. Date of Earliest Transaction (Month/Day/Year)
01/27/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock, par value $.0001 per share	01/27/2026		M		55,902(1)	A	$0	123,555	D
Common Stock, par value $.0001 per share	01/27/2026		F		22,804(2)	D	$6.82	100,751	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Units	(3)	01/27/2026		M			55,902	(3)	(3)	Common Stock, par value $.0001 per share	55,902	$0	55,903	D

Explanation of Responses:

1. Represents the acquisition of Common Stock from the vesting of one-third of the restricted stock units ("RSUs") granted on January 27, 2024.

2. Represents the withholding by the Issuer of shares of Common Stock (based on $6.82 per share, the closing stock price on January 27, 2026) to satisfy tax withholding obligations associated with the vesting of RSUs and the consequent issuance of Common Stock.

3. RSUs represent contingent rights to receive Common Stock on a one-for-one basis. The RSUs vest over three years, one-third on each of the first three anniversaries of the date of grant.

	/s/ Diem Nguyen	01/28/2026
	** Signature of Reporting Person	Date
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