CTKB Form 4: Director acquires 6,107 Cytek shares via RSU vesting

Rhea-AI Filing Summary

Cytek Biosciences (CTKB) reported an insider equity transaction by a company director on 11/18/2025. The filing shows that 6,107 shares of common stock were acquired through the vesting and settlement of restricted stock units (RSUs), coded as transaction type “M,” which reflects the conversion of a derivative security into common stock.

After this transaction, the director beneficially owns 10,178 shares of Cytek common stock directly and continues to hold 63,111 RSUs. Each RSU represents the right to receive one share of common stock. The RSU award vests over time in tranches on specific dates, including portions vesting on August 18, November 18, March 10, May 18 and August 18 of future years until the award is fully vested.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Chin Richard

(Last) (First) (Middle)

C/O CYTEK BIOSCIENCES, INC.

47215 LAKEVIEW BOULEVARD

(Street)

FREMONT CA 94538

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Cytek Biosciences, Inc. [ CTKB ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
11/18/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	11/18/2025		M		6,107	A	(1)	10,178	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Units	(1)	11/18/2025		M			6,107	(2)	(2)	Common Stock	6,107	$0	63,111	D

Explanation of Responses:

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

2. 2/36 of the total shares subject to the RSU Award shall vest on August 18, 2025; 3/36 of the total shares subject to the RSU Award shall vest on November 18, 2025 and each November 18 thereafter; 3/36 of the total shares underlying the RSU Award shall vest on March 10, 2026 and each March 10 thereafter; 3/36 of the total shares underlying the RSU Award vesting shall vest on May 18, 2026 and each May 18 thereafter; and 3/36 of the total shares underlying the RSU Award shall vest on August 18, 2026 and each August 18 thereafter, until fully vested.

	/s/ Valerie Barnett, Attorney-in-Fact	11/20/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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FAQ

What insider transaction did Cytek Biosciences (CTKB) report in this Form 4?

The Form 4 reports that a director of Cytek Biosciences acquired 6,107 shares of common stock on 11/18/2025 through the conversion of restricted stock units.

How many Cytek Biosciences (CTKB) shares does the director own after the transaction?

Following the reported transaction, the director beneficially owns 10,178 shares of Cytek Biosciences common stock in direct ownership.

What is the size of the directors remaining RSU holdings in Cytek Biosciences?

After the conversion of some units, the director continues to hold 63,111 restricted stock units (RSUs), each representing a contingent right to receive one share of common stock.

How many restricted stock units vested and converted to Cytek (CTKB) shares?

A total of 6,107 RSUs vested and were settled into the same number of Cytek Biosciences common shares on 11/18/2025.

What does the transaction code M mean in this Cytek Biosciences Form 4?

The transaction is coded as M, indicating the exercise or conversion of a derivative security (here, RSUs) into common stock, rather than an open-market purchase or sale.

How do the Cytek Biosciences RSUs vest over time for this director?

The RSU award vests in scheduled tranches: 2/36 of the total shares vest on August 18, 2025, and several 3/36 tranches vest on November 18, March 10, May 18, and August 18 of specified years until the award is fully vested.