[Form 4] Cytek Biosciences, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Cytek Biosciences (CTKB) president and CEO, who also serves as a director, reported several equity transactions on November 18, 2025 related to restricted stock units (RSUs). Multiple RSU awards were converted into common stock, with 6,758, 11,781, 22,100 and 29,002 shares of common stock issued as each RSU grant vested.

To cover tax withholding from these vestings, the issuer withheld and received back 2,660, 4,636, 8,697 and 11,413 shares at a price of $5.53 per share. After the reported transactions, the executive beneficially owned 5,356,652 shares of Cytek common stock directly, and continued to hold RSU awards covering 4,514, 62,837, 206,273 and 386,699 units that will vest over multiple years on specified quarterly and annual dates.

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

OMB Number:			3235-0287
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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^*

Jiang Wenbin

(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
X	Officer (give title below)		Other (specify below)
	PRESIDENT AND CEO

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		6,758	A	(1)	5,321,175	D
Common Stock	11/18/2025		F		2,660(2)	D	$5.53	5,318,515	D
Common Stock	11/18/2025		M		11,781	A	(1)	5,330,296	D
Common Stock	11/18/2025		F		4,636(2)	D	$5.53	5,325,660	D
Common Stock	11/18/2025		M		22,100	A	(1)	5,347,760	D
Common Stock	11/18/2025		F		8,697(2)	D	$5.53	5,339,063	D
Common Stock	11/18/2025		M		29,002	A	(1)	5,368,065	D
Common Stock	11/18/2025		F		11,413(2)	D	$5.53	5,356,652	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			6,758	(3)	(3)	Common Stock	6,758	$0	4,514	D
Restricted Stock Units	(1)	11/18/2025		M			11,781	(4)	(4)	Common Stock	11,781	$0	62,837	D
Restricted Stock Units	(1)	11/18/2025		M			22,100	(5)	(5)	Common Stock	22,100	$0	206,273	D
Restricted Stock Units	(1)	11/18/2025		M			29,002	(6)	(6)	Common Stock	29,002	$0	386,699	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. Represents the number of shares withheld by and surrendered to the Issuer on November 18, 2025, to satisfy tax withholding obligations that arose in connection with the vesting of the RSU Award.

3. The shares subject to the RSU Award shall vest quarterly over four years, with 4/48th of the total shares underlying the RSU Award vesting on May 18, 2022 and 3/48th of the total shares underlying the RSU Award vesting each subsequent quarter thereafter on August 18, November 18, February 18 and May 18.

4. 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, 2023 and each May 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on August 18, 2023 and each August 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on November 18, 2023 and each November 18 thereafter; and 4/48 of the total shares underlying the RSU Award vesting on March 10, 2024 and each March 10 thereafter, until fully vested.

5. 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, 2024 and each May 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on August 18, 2024 and each August 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on November 18, 2024 and each November 18 thereafter; and 4/48 of the total shares underlying the RSU Award vesting on March 10, 2025 and each March 10 thereafter.

6. 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.

	/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.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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FAQ

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

The filing reports the Cytek Biosciences president and CEO, who is also a director, converting several restricted stock unit (RSU) awards into common stock on November 18, 2025, and related share withholdings for taxes.

How many Cytek (CTKB) RSUs vested into common shares in this filing?

Four RSU awards vested into common stock in amounts of 6,758, 11,781, 22,100 and 29,002 shares of Cytek Biosciences common stock.

How were taxes handled for the Cytek (CTKB) CEO RSU vesting?

To satisfy tax withholding obligations from the RSU vesting, the issuer withheld and received back 2,660, 4,636, 8,697 and 11,413 shares of common stock at a price of $5.53 per share.

How many Cytek Biosciences (CTKB) shares does the reporting person own after these transactions?

Following the reported transactions, the reporting person beneficially owned 5,356,652 shares of Cytek Biosciences common stock directly.

What RSU balances remain outstanding for the Cytek (CTKB) CEO?

After these transactions, the executive still held restricted stock units covering 4,514, 62,837, 206,273 and 386,699 units, each representing a contingent right to receive one share of common stock.

What are the vesting schedules for the Cytek (CTKB) RSU awards mentioned?

The RSU awards vest over four-year periods in quarterly and annual installments, with specific fractions (such as 2/48, 3/48 and 4/48) vesting on set dates including May 18, August 18, November 18, February 18 and March 10 of various years, until fully vested.