X0306 4 2021-04-16 0 0001020214 CERUS CORP CERS 0001377258 Greenman William Mariner C/O CERUS CORPORATION 1220 CONCORD AVE SUITE 600 CONCORD CA 94520 1 1 0 0 President and CEO Common Stock 2021-04-16 4 M 0 550000 2.70 A 1652531 D Common Stock 2021-04-16 4 F 0 233859 6.35 D 1418672 D Option (Right to Buy) 2.70 2021-04-16 4 M 0 550000 D 2021-04-18 Common Stock 550000 0 D Represents a net exercise of outstanding stock options. These shares were withheld by Issuers for payment of the exercise price, based on the market price of Issuers common stock on April 15, 2021 of $6.35 in accordance with the terms of the Issuers Amended and Restated 2008 Equity Incentive Plan. The Reporting Person elected to pay the withholding taxes in cash. One eighth (1/8th) of the shares subject to the Option vested six (6) months after the grant date, and one forty-eighth (1/48th) of the shares subject to the Option vested on the first day of each month thereafter. Not applicable. William M. Greenman by Chrystal Menard, attorney-in-fact 2021-04-20