Key facts
- This page summarizes William D. McCombe's Form 4 filing for Cytek Biosciences, Inc. (CTKB).
- 9 reported transactions and 3 derivative rows are listed below.
- Accepted by SEC: 20 Aug 2026, 16:34.
William D. McCombe - 18 Aug 2026 Form 4 Insider Report for Cytek Biosciences, Inc. (CTKB)
- Reporting relationship
- Chief Financial Officer
- Issuer ticker
- CTKB
- Reported as of
- 18 Aug 2026
- Net transaction value
- $0
- SEC form
- 4
- Accepted by SEC
- 20 Aug 2026, 16:34:02 UTC
- Prior SEC filing
- 20 May 2026
- Source filing
- View source filing
- Reporting owner signature
- /s/ Gordon Ho, Attorney-in-Fact
Source evidence
Original filing metadata and source links for verification.
4 source fields
Reporting owner
1 detail
Key filing fact
William D. McCombe filed Form 4 for Cytek Biosciences, Inc. (CTKB) on 20 Aug 2026.
Change
- Previous filing in this sequence was filed on 20 May 2026.
- 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
View source filing
Ownership activity is grounded in SEC Form 4 disclosures.
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/ Gordon Ho, Attorney-in-Fact
- Signature date
- 20 Aug 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 %
- +5.7%
- Price
- Shares after
- 117,497
- Date
- 18 Aug 2026
- Ownership
- Direct
- Footnotes
- F1
CTKB
transaction
Common Stock
Tax liability
- Transaction value
- Shares
- -2,111
- Change %
- -1.8%
- Price
- $4.67*
- Shares after
- 115,386
- Date
- 18 Aug 2026
- Ownership
- Direct
- Footnotes
- F2
CTKB
transaction
Common Stock
Options Exercise
- Transaction value
- Shares
- +13,051
- Change %
- +11%
- Price
- Shares after
- 128,437
- Date
- 18 Aug 2026
- Ownership
- Direct
- Footnotes
- F1
CTKB
transaction
Common Stock
Tax liability
- Transaction value
- Shares
- -4,392
- Change %
- -3.4%
- Price
- $4.67*
- Shares after
- 124,045
- Date
- 18 Aug 2026
- Ownership
- Direct
- Footnotes
- F2
CTKB
transaction
Common Stock
Options Exercise
- Transaction value
- Shares
- +16,049
- Change %
- +13%
- Price
- Shares after
- 140,094
- Date
- 18 Aug 2026
- Ownership
- Direct
- Footnotes
- F1
CTKB
transaction
Common Stock
Tax liability
- Transaction value
- Shares
- -5,401
- Change %
- -3.9%
- Price
- $4.67*
- Shares after
- 134,693
- Date
- 18 Aug 2026
- Ownership
- Direct
- Footnotes
- F2
Reported derivative securities
Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.
CTKB
transaction
Derivative
Restricted Stock Units
Options Exercise
- Transaction value
- Shares
- -6,320
- Change %
- -12%
- Price
- $0.000000*
- Shares after
- 44,249
- Date
- 18 Aug 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 6,320
- Exercise price
- Footnotes
- F1, F3
CTKB
transaction
Derivative
Restricted Stock Units
Options Exercise
- Transaction value
- Shares
- -13,051
- Change %
- -8.8%
- Price
- $0.000000*
- Shares after
- 134,862
- Date
- 18 Aug 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 13,051
- Exercise price
- Footnotes
- F1, F4
CTKB
transaction
Derivative
Restricted Stock Units
Options Exercise
- Transaction value
- Shares
- -16,049
- Change %
- -6.5%
- Price
- $0.000000*
- Shares after
- 230,042
- Date
- 18 Aug 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 16,049
- Exercise price
- Footnotes
- F1, F5
* marks a reported price that did not pass the local price check.
Additional SEC filing notes
Filing notes and footnotes
Explanation of responses 5 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 August 18, 2026 to satisfy tax withholding obligations that arose in connection with the vesting of the RSU Award.
Footnote F3
The shares underlying 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; 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 F4
The shares underlying 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.
Footnote F5
The shares underlying 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 on August 18, 2026 and each August 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on 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.