X0306 4 2018-11-22 0001010086 SIGA TECHNOLOGIES INC SIGA 0001139301 ROSE ERIC A MD C/O SIGA TECHNOLOGIES, INC. 31 EAST 62ND STREET NEW YORK NY 10065 true Common Stock, par value $.0001 per share 2018-11-22 4 M 0 200000 0 A 1098990 D Common Stock, par value $.0001 per share 2018-11-22 4 F 0 105896 5.55 D 993094 D Restricted Stock Units 2018-11-22 4 M 0 200000 0 D Common Stock, par value $.0001 per share 200000 100000 D SIGA Technologies, Inc. (the "Issuer") has certain tax withholding obligations associated with the vesting of restricted stock units ("RSUs") and the consequent issuance of Common Stock of the Issuer. This Form 4 reports the surrender to the Issuer by the Reporting Person of 105,896 shares of Common Stock -- granted in the form of RSUs on November 22, 2016 -- in order to satisfy those withholding tax obligations. Represents vesting of certain RSUs granted on November 22, 2016 and the consequent issuance of Common Stock of the Issuer to the Reporting Person. The RSUs vest over three years, one-third on each of the first three anniversaries of the date of grant. The shares of Common Stock reported in this Form 4 were issued in respect of RSUs that vested on November 22, 2017 and November 22, 2018. Each RSU converts into one share of Common Stock of the Issuer on a one for one basis. /s/ Eric A Rose, M.D. 2018-11-26