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

Rhea-AI Filing Summary

Cytek Biosciences (CTKB) chief technology officer and director reported multiple equity transactions on November 18, 2025 related to previously granted restricted stock units (RSUs). Several RSU tranches were converted into common stock, including blocks of 1,981, 7,363, 5,525 and 6,162 shares, reflecting ongoing vesting of long-term equity awards. To cover tax withholding from these vestings, a total of 4,? (aggregate of 483, 1,793, 1,346 and 1,501) shares were withheld and surrendered to the company at a price of $5.53 per share, rather than being sold on the open market. After these transactions, the insider directly beneficially owned 6,073,327 shares of Cytek common stock. The RSU grants continue to 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

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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^*

Yan Ming

(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)
	CHIEF TECHNOLOGY 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		1,981	A	(1)	6,059,400	D
Common Stock	11/18/2025		F		483(2)	D	$5.53	6,058,917	D
Common Stock	11/18/2025		M		7,363	A	(1)	6,066,280	D
Common Stock	11/18/2025		F		1,793(2)	D	$5.53	6,064,487	D
Common Stock	11/18/2025		M		5,525	A	(1)	6,070,012	D
Common Stock	11/18/2025		F		1,346(2)	D	$5.53	6,068,666	D
Common Stock	11/18/2025		M		6,162	A	(1)	6,074,828	D
Common Stock	11/18/2025		F		1,501(2)	D	$5.53	6,073,327	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			1,981	(3)	(3)	Common Stock	1,981	$0	1,332	D
Restricted Stock Units	(1)	11/18/2025		M			7,363	(4)	(4)	Common Stock	7,363	$0	39,277	D
Restricted Stock Units	(1)	11/18/2025		M			5,525	(5)	(5)	Common Stock	5,525	$0	51,569	D
Restricted Stock Units	(1)	11/18/2025		M			6,162	(6)	(6)	Common Stock	6,162	$0	82,175	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 Form 4 reports that Cytek Biosciences' chief technology officer and director had multiple restricted stock unit (RSU) tranches vest on November 18, 2025, which were settled in shares of common stock with a portion of shares withheld to satisfy tax obligations.

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

Following the reported RSU vesting and related tax share withholdings on November 18, 2025, the reporting person directly beneficially owned 6,073,327 shares of Cytek Biosciences common stock.

What types of equity awards are involved in this Cytek Biosciences (CTKB) Form 4?

The transactions involve restricted stock units (RSUs), which represent a right to receive one share of Cytek Biosciences common stock per unit. As the RSUs vest, they are settled in common shares according to the specified vesting schedules.

Were Cytek Biosciences (CTKB) shares sold into the market in this Form 4?

The Form 4 shows shares labeled under transaction code "F" that were withheld and surrendered to the issuer on November 18, 2025 to satisfy tax withholding obligations arising from RSU vesting, at a price of $5.53 per share.

What are the vesting terms of the Cytek Biosciences (CTKB) RSU awards mentioned?

The RSU awards vest over four-year periods with detailed schedules using fractional installments such as 4/48 or 3/48 of the total shares, vesting on quarterly or specific calendar dates including May 18, August 18, November 18, February 18, and March 10 until fully vested.

What was the tax withholding share price on the Cytek Biosciences (CTKB) Form 4 transactions?

For the shares withheld to cover taxes in connection with the RSU vesting on November 18, 2025, the Form 4 reports a price of $5.53 per share.