X0306 4 2017-11-27 0 0001082923 STAMPS.COM INC STMP 0001254776 MCBRIDE KENNETH THOMAS 1990 E. GRAND AVE. EL SEGUNDO CA 90245 1 1 0 0 Chairman & CEO Common Stock 2017-11-27 4 M 0 71733 32.41 A 73599 D Common Stock 2017-11-27 4 M 0 70000 32.41 A 143599 D Common Stock 2017-11-27 4 S 0 141733 180.0145 D 1866 D Common Stock 2017-11-28 4 M 0 400 32.41 A 2266 D Common Stock 2017-11-28 4 S 0 400 180.5938 D 1866 D Stock Option(Common Stock) 32.41 2017-11-27 4 M 0 71733 0.00 D 2014-10-19 2024-09-19 Common Stock 71733 313852 D Stock Option(common Stock) 32.41 2017-11-27 4 M 0 70000 0.00 D 2015-10-19 2024-09-19 Common Stock 70000 243852 D Stock Option(Common Stock) 32.41 2017-11-28 4 M 0 400 0.00 D 2014-10-19 2024-09-19 Common Stock 400 243452 D This sale was executed pursuant to a prearranged trading plan compliant with Rule 10b5-1. This sale price reflects a weighted average of multiple prices ranging from $180.00 to $180.7250. Full information regarding the number of shares sold at each price will be provided to the Securities and Exchange Commission staff, the issuer or any security holder, upon request. This sale price reflects a weighted average of multiple prices ranging from $180.3750 to $180.80. Full information regarding the number of shares sold at each price will be provided to the Securities and Exchange Commission staff, the issuer or any security holder, upon request. /s/ David M Zlotchew, by Power of Attorney for Kenneth T McBride 2017-11-29