X0508 4 2023-08-18 0 0001831915 Cytek Biosciences, Inc. CTKB 0001951234 Williams Paul Christopher C/O CYTEK BIOSCIENCES, INC. 47215 LAKEVIEW BOULEVARD FREMONT CA 94538 0 1 0 0 Chief Operating Officer 0 Common Stock 2023-08-18 4 M 0 920 A 1294 D Common Stock 2023-08-18 4 F 0 359 8.46 D 935 D Restricted Stock Units 2023-08-18 4 M 0 920 0.00 D 08/18/2023 920 13193 D Each Restricted Stock Unit (the "RSU Award") represents a contingent right to receive one share of the Issuer's common stock. Represents the number of shares withheld by and surrendered to the Issuer on August 18, 2023, to satisfy tax withholding obligations that arose in connection with the vesting of the RSU Award. The shares subject to the RSU Award shall vest over four years with 2/48 of the total shares underlying the RSU Award vesting on May 18, 2023 and each May 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on August 18, 2023 and each August 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on November 18, 2023 and each November 18 thereafter; and 4/48 of the total shares underlying the RSU Award vesting each March 10, 2024 and each March 10 thereafter, until fully vested. /s/ Valerie Barnett, Attorney-in-Fact for Paul Christopher Williams 2023-08-21