Cytek Biosciences (NASDAQ: CTKB) director gains 2,908 shares via RSU vesting

Rhea-AI Filing Summary

Cytek Biosciences director Michael Holder reported the vesting and exercise of restricted stock units into common shares as part of his equity compensation. On March 10, 2026, 2,908 RSUs converted into 2,908 shares of common stock at no cash cost, lifting his directly held common stock to 15,267 shares after the transaction.

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

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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^*

Holder Michael

(Last) (First) (Middle)

C/O CYTEK BIOSCIENCES, INC.

47215 LAKEVIEW BLVD.

(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)
03/10/2026

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	03/10/2026		M		2,908	A	(1)	15,267	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)	03/10/2026		M			2,908	(2)	(2)	Common Stock	2,908	$0	10,911	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, 2024; 3/36 of the total shares subject to the RSU Award shall vest on November 18, 2024 and each November 18 thereafter; 4/36 of the total shares underlying the RSU Award shall vest on March 10, 2025 and each March 10 thereafter; 2/36 of the total shares underlying the RSU Award vesting shall vest on May 18, 2025 and each May 18 thereafter; and 3/36 of the total shares underlying the RSU Award shall vest on August 18, 2025 and each August 18 thereafter, until fully vested.

	/s/ Valerie Barnett, Attorney-in-Fact	03/12/2026
	** 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 for Michael Holder?

Cytek Biosciences director Michael Holder reported an equity compensation event. On March 10, 2026, 2,908 restricted stock units converted into 2,908 shares of common stock at a price of $0.00 per share, reflecting vesting rather than an open-market purchase.

Did Michael Holder buy or sell Cytek Biosciences (CTKB) shares on the open market?

The Form 4 shows no open-market buying or selling. Instead, 2,908 restricted stock units vested and were converted into 2,908 shares of common stock at $0.00 per share, a standard compensation-related derivative exercise, not a discretionary market trade.

How many Cytek Biosciences (CTKB) shares does Michael Holder own after this Form 4?

Following the March 10, 2026 transactions, Michael Holder directly owns 15,267 shares of Cytek Biosciences common stock. This reflects the addition of 2,908 shares received upon vesting and conversion of restricted stock units into common stock at no cash exercise price.

What do the restricted stock unit terms mean in Cytek Biosciences (CTKB) Form 4?

Each restricted stock unit represents a right to receive one share of common stock. The award vests in scheduled fractions of the total grant on specific dates, including August 18, November 18, March 10, and May 18 each year, until the grant is fully vested.

How many restricted stock units did Michael Holder exercise at Cytek Biosciences (CTKB)?

Michael Holder exercised 2,908 restricted stock units, converting them into 2,908 shares of Cytek Biosciences common stock at $0.00 per share. This single derivative exercise is recorded as one exercise event in the Form 4 transaction summary for March 10, 2026.

Is the Cytek Biosciences (CTKB) Form 4 for Michael Holder a routine compensation event?

Yes. The filing describes vesting and conversion of restricted stock units into common shares at $0.00 per share. Such RSU vesting is a standard component of director or executive compensation and does not, by itself, indicate an open-market bullish or bearish trading decision.