X0306 4 2018-11-12 0001010086 SIGA TECHNOLOGIES INC SIGA 0001301548 Hruby Dennis E C/O SIGA TECHNOLOGIES, INC. 31 EAST 62ND STREET NEW YORK NY 10065 true VP & Chief Scientific Officer Common Stock, Par Value $.0001 Per Share 2018-11-12 4 S 0 18901 4.96 D 228564 D Common Stock, Par Value $.0001 Per Share 2018-11-13 4 S 0 31099 5.29 D 197465 D The price reported in Column 4 is a weighted average price. These shares were sold on November 12, 2018 in multiple transactions at prices ranging from $4.90 to $5.06, inclusive, and on November 13, 2018 in multiple transactions at prices ranging from $5.03 to $5.48, inclusive. The reporting person undertakes to provide to SIGA Technologies, Inc., any security holder of SIGA Technologies, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (1) to this Form 4. /s/ Dennis E. Hruby 2018-11-13