SIGA TECHNOLOGIES INC

On* November 4, 2026,Dennis Hruby, Ph.D., informed the Company of his intent to retire as Executive Vice President and Chief Scientific Officer of the Company, and Dr. Hruby’s employment with the Company will end, effective November 9, 2026 (the “Retirement Date”). Dr. Hruby’s departure is without any disagreements with management. To help ensure a smooth transition of his responsibilities, Dr. Hruby and the Company agreed that he will transition to a consulting role with the Company. The Company and Dr. Hruby have entered into a retirement and consulting agreement (the “Retirement and Consulting Agreement”) pursuant to which Dr. Hruby will provide the Company consulting services from his Retirement Date through May 9, 2028 (*the “Consulting Period”). During the Consulting Period, Dr. Hruby will be paid a monthly consulting fee of $20,000. In addition, pursuant to the Retirement and Consulting Agreement, Dr. Hruby is entitled to receive the following: (i) continued payment of his base salary as severance pay for a period of twenty-four months following the Retirement Date; (ii) accelerated vesting of all his unvested restricted stock units; and (iii) continued vesting of certain performance based restricted stock units, according to their terms. The Retirement and Consulting Agreement is subject to a customary release of claims in the Company’s favor.

None of the Company's directors or officers adopted, modified or terminated a Rule10b5-1 trading arrangement or a non-Rule10b5-1 trading arrangement during the Company's quarter ended* September 30, 2026*, as such terms are defined under Item408(a) of Regulation S-K.