Glenn P. Muir - 10 Jun 2026 Form 4 Insider Report for Cytek Biosciences, Inc. (CTKB)

Reporting relationship: Director
Issuer ticker: CTKB
Reported as of: 10 Jun 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 12 Jun 2026, 19:31:29 UTC
Prior SEC filing: 29 May 2026
Next SEC filing: 20 Aug 2026
Source filing: View source filing
Reporting owner signature: /s/ Valerie Barnett, Attorney-in-Fact

Key filing fact

Glenn P. Muir filed Form 4 for Cytek Biosciences, Inc. (CTKB) on 12 Jun 2026.

Key facts

This page summarizes Glenn P. Muir's Form 4 filing for Cytek Biosciences, Inc. (CTKB).
2 reported transactions and 2 derivative rows are listed below.
Accepted by SEC: 12 Jun 2026, 19:31.

Change

Previous filing in this sequence was filed on 29 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

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001181190 Primary reporting owner

MUIR GLENN P

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

Reported derivative securities

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

CTKB transaction Derivative

Restricted Stock Units

Award

Transaction value
Shares: +55,555
Change %
Price: $0.000000^*
Shares after: 55,555
Date: 10 Jun 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 55,555
Exercise price
Footnotes: F1, F2

CTKB transaction Derivative

Director Stock Option (right to buy)

Award

Transaction value
Shares: +29,835
Change %
Price: $0.000000^*
Shares after: 29,835
Date: 10 Jun 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 29,835
Exercise price: $4.05
Footnotes: F3

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

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 3 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

2/36 of the total shares subject to the RSU Award shall vest on August 18, 2026; 3/36 of the total shares subject to the RSU Award shall vest on November 18, 2026 and each November 18 thereafter; 4/36 of the total shares underlying the RSU Award shall vest on March 10, 2027 and each March 10 thereafter; 3/36 of the total shares underlying the RSU Award vesting shall vest on May 18, 2027 and each May 18 thereafter; and 3/36 of the total shares underlying the RSU Award shall vest on August 18, 2027 and each August 18 thereafter, until fully vested.

Footnote F3

1/36 of the total shares subject to the option shall vest monthly over 3 years following the grant date of June 10, 2026.