Philippe Busque - 18 Nov 2025 Form 4 Insider Report for Cytek Biosciences, Inc. (CTKB)

Role
SVP, GLOBAL SALES AND SERVICES
Signature
/s/ Valerie Barnett, Attorney-in-Fact
Issuer symbol
CTKB
Transactions as of
18 Nov 2025
Net transactions value
-$10,424
Form type
4
Filing time
20 Nov 2025, 19:07:37 UTC
Previous filing
20 Aug 2025
SEC
View on sec.gov

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
Busque Philippe SVP, GLOBAL SALES AND SERVICES C/O CYTEK BIOSCIENCES, INC., 47215 LAKEVIEW BLVD., FREMONT /s/ Valerie Barnett, Attorney-in-Fact 20 Nov 2025 0001991396

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction CTKB Common Stock Options Exercise +1,536 +6.6% 24,952 18 Nov 2025 Direct F1
transaction CTKB Common Stock Tax liability $2,173 -393 -1.6% $5.53 24,559 18 Nov 2025 Direct F2
transaction CTKB Common Stock Options Exercise +2,210 +9% 26,769 18 Nov 2025 Direct F1
transaction CTKB Common Stock Tax liability $3,124 -565 -2.1% $5.53 26,204 18 Nov 2025 Direct F2
transaction CTKB Common Stock Options Exercise +3,625 +14% 29,829 18 Nov 2025 Direct F1
transaction CTKB Common Stock Tax liability $5,126 -927 -3.1% $5.53 28,902 18 Nov 2025 Direct F2

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Underlying Class Amount Exercise Price Ownership Footnotes
transaction CTKB Restricted Stock Units Options Exercise $0 -1,536 -15% $0.000000 8,714 18 Nov 2025 Common Stock 1,536 Direct F1, F3
transaction CTKB Restricted Stock Units Options Exercise $0 -2,210 -9.7% $0.000000 20,628 18 Nov 2025 Common Stock 2,210 Direct F1, F4
transaction CTKB Restricted Stock Units Options Exercise $0 -3,625 -7% $0.000000 48,338 18 Nov 2025 Common Stock 3,625 Direct F1, F5
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id Content
F1 Each Restricted Stock Unit (the "RSU Award") represents a contingent right to receive one share of the Issuer's common stock.
F2 Represents the number of shares withheld by and surrendered to the Issuer on November 18, 2025, to satisfy tax withholding obligations that arose in connection with the vesting of the RSU Award.
F3 The shares subject to the RSU Award shall vest over four years with 13/48 of the total shares underlying the RSU Award vesting on May 18, 2024; 3/48 of the total shares underlying the RSU Award vesting on August 18, 2024 and each August 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on November 18, 2024 and each November 18 thereafter; 4/48 of the total shares underlying the RSU Award vesting on March 10, 2025 and each March 10 thereafter; and 2/48 of the total shares underlying the RSU Award vesting on May 18, 2025 and each May 18 thereafter.
F4 The shares subject to the RSU Award shall vest over 4 years with 2/48 of the total shares underlying the RSU Award vesting on May 18, 2024 and each May 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on August 18, 2024 and each August 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on November 18, 2024 and each November 18 thereafter; and 4/48 of the total shares underlying the RSU Award vesting on March 10, 2025 and each March 10 thereafter.
F5 The shares subject to the RSU Award shall vest over 4 years with 2/48 of the total shares underlying the RSU Award vesting on May 18, 2025 and each May 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on August 18, 2025 and each August 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on November 18, 2025 and each November 18 thereafter; and 4/48 of the total shares underlying the RSU Award vesting on March 10, 2026 and each March 10 thereafter, until fully vested.