William D. McCombe - 10 Mar 2026 Form 4 Insider Report for Cytek Biosciences, Inc. (CTKB)

Reporting relationship: Chief Financial Officer
Issuer ticker: CTKB
Reported as of: 10 Mar 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 12 Mar 2026, 16:37:27 UTC
Prior SEC filing: 20 Nov 2025
Next SEC filing: 20 May 2026
Source filing: View source filing
Reporting owner signature: /s/ Valerie Barnett, Attorney-in-Fact

Key filing fact

William D. McCombe filed Form 4 for Cytek Biosciences, Inc. (CTKB) on 12 Mar 2026.

Key facts

This page summarizes William D. McCombe's Form 4 filing for Cytek Biosciences, Inc. (CTKB).
8 reported transactions and 4 derivative rows are listed below.
Accepted by SEC: 12 Mar 2026, 16:37.

Change

Previous filing in this sequence was filed on 20 Nov 2025.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001878824 Primary reporting owner

McCombe William D.

Relationship: Chief Financial Officer
Address: C/O CYTEK BIOSCIENCES, INC., 47215 LAKEVIEW BOULEVARD, FREMONT
Signature: /s/ Valerie Barnett, Attorney-in-Fact
Signature date: 12 Mar 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

CTKB transaction

Common Stock

Options Exercise

Transaction value
Shares: +6,320
Change %: +7.8%
Price
Shares after: 87,034
Date: 10 Mar 2026
Ownership: Direct
Footnotes: F1

CTKB transaction

Common Stock

Tax liability

Transaction value
Shares: -2,603
Change %: -3%
Price: $4.23^*
Shares after: 84,431
Date: 10 Mar 2026
Ownership: Direct
Footnotes: F2

CTKB transaction

Common Stock

Options Exercise

Transaction value
Shares: +17,401
Change %: +21%
Price
Shares after: 101,832
Date: 10 Mar 2026
Ownership: Direct
Footnotes: F1

CTKB transaction

Common Stock

Tax liability

Transaction value
Shares: -7,145
Change %: -7%
Price: $4.23^*
Shares after: 94,687
Date: 10 Mar 2026
Ownership: Direct
Footnotes: F2

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

CTKB transaction Derivative

Employee Stock Option (right to buy)

Award

Transaction value
Shares: +136,205
Change %
Price: $0.000000^*
Shares after: 136,205
Date: 10 Mar 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 136,205
Exercise price: $4.23
Footnotes: F3

CTKB transaction Derivative

Restricted Stock Units

Award

Transaction value
Shares: +256,790
Change %
Price: $0.000000^*
Shares after: 256,790
Date: 10 Mar 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 256,790
Exercise price
Footnotes: F1, F4

CTKB transaction Derivative

Restricted Stock Units

Options Exercise

Transaction value
Shares: -6,320
Change %: -10%
Price: $0.000000^*
Shares after: 56,889
Date: 10 Mar 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 6,320
Exercise price
Footnotes: F1, F5

CTKB transaction Derivative

Restricted Stock Units

Options Exercise

Transaction value
Shares: -17,401
Change %: -10%
Price: $0.000000^*
Shares after: 156,613
Date: 10 Mar 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 17,401
Exercise price
Footnotes: F1, F6

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 6 footnotes

Footnote F1

Each Restricted Stock Unit (the "RSU Award") represents a contingent right to receive one share of the Issuer's common stock.

Footnote F2

Represents the number of shares withheld by and surrendered to the Issuer on March 10, 2026, to satisfy tax withholding obligations that arose in connection with the vesting of the RSU Award.

Footnote F3

The shares subject to the stock option shall vest over 4 years with 1/48 of the total shares underlying the stock option vesting on April 10, 2026 and each month thereafter until fully vested.

Footnote 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, 2026 and each May 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting August 18, 2026 and each August 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting November 18, 2026 and each November 18 thereafter; and 4/48 of the total shares underlying the RSU Award vesting on March 10, 2027 and each March 10 thereafter, until fully vested.

Footnote F5

The shares subject to the RSU Award shall vest over 4 years with 12/48 of the total shares underlying the RSU Award vesting on May 18, 2025; 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 3/48 of the total shares underlying the RSU Award vesting on March 10, 2026 and each March 10 thereafter; and 3/48 of the total shares underlying the RSU Award vesting on May 18, 2026 and each May 18 thereafter.

Footnote F6

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.