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

Rhea-AI Filing Summary

Cytek Biosciences, Inc. insider activity: the company’s Chief Legal Officer reported multiple transactions on common stock tied to vesting of restricted stock units (RSUs) on November 18, 2025. Several RSU awards were converted into common shares, each RSU representing a right to receive one share of Cytek common stock.

On the same date, shares were also withheld and surrendered to Cytek to cover tax withholding obligations at a price of $5.53 per share. After these RSU conversions and tax withholdings, the reporting person directly beneficially owned 115,641 shares of Cytek common stock. The RSU awards vest over four-year schedules with quarterly and annual vesting dates as described in the filing.

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
Estimated average burden
hours per response:			0.5

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^*

Barnett Valerie

(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)

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

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		2,016	A	(1)	101,167	D
Common Stock	11/18/2025		F		649(2)	D	$5.53	100,518	D
Common Stock	11/18/2025		M		3,681	A	(1)	104,199	D
Common Stock	11/18/2025		F		1,184(2)	D	$5.53	103,015	D
Common Stock	11/18/2025		M		7,735	A	(1)	110,750	D
Common Stock	11/18/2025		F		2,487(2)	D	$5.53	108,263	D
Common Stock	11/18/2025		M		10,875	A	(1)	119,138	D
Common Stock	11/18/2025		F		3,497(2)	D	$5.53	115,641	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			2,016	(3)	(3)	Common Stock	2,016	$0	1,346	D
Restricted Stock Units	(1)	11/18/2025		M			3,681	(4)	(4)	Common Stock	3,681	$0	19,642	D
Restricted Stock Units	(1)	11/18/2025		M			7,735	(5)	(5)	Common Stock	7,735	$0	72,197	D
Restricted Stock Units	(1)	11/18/2025		M			10,875	(6)	(6)	Common Stock	10,875	$0	145,013	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	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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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FAQ

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

The filing reports that the Chief Legal Officer of Cytek Biosciences, Inc. completed multiple transactions on November 18, 2025 in connection with the vesting of several restricted stock unit (RSU) awards, which were converted into shares of Cytek common stock.

Who is the reporting person in the Cytek Biosciences (CTKB) Form 4 and what is their role?

The reporting person is an officer of Cytek Biosciences, Inc. serving as the company’s Chief Legal Officer, and the filing is made by this single reporting person.

How many Cytek Biosciences (CTKB) shares does the insider own after the reported transactions?

Following the RSU conversions and related tax share withholdings reported in the Form 4, the Chief Legal Officer directly beneficially owned 115,641 shares of Cytek Biosciences, Inc. common stock.

What is an RSU Award in the context of Cytek Biosciences (CTKB)?

Each Restricted Stock Unit (RSU) Award represents a contingent right to receive one share of Cytek Biosciences common stock upon vesting, as described in the explanation of responses.

How were taxes handled on the Cytek Biosciences (CTKB) RSU vesting reported here?

The filing states that certain shares were withheld by and surrendered to Cytek on November 18, 2025 to satisfy tax withholding obligations arising from RSU vesting, at a share price of $5.53.

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

The RSU awards vest over four-year periods with specified fractions of the total shares vesting on dates including May 18, August 18, November 18, and March 10 in various years, until each award is fully vested.

Does the Cytek Biosciences (CTKB) Form 4 involve derivative securities?

Yes. The filing includes restricted stock units in Table II, which are derivative securities that convert into common stock at an exercise price of $0 when they vest, with specified amounts of common shares underlying each RSU award.