Cytek (CTKB) Insider Report: Multiple RSU Vests and Tax-Withholding Details

Rhea-AI Filing Summary

Insider transactions by Cytek Biosciences (CTKB): The company's President and CEO and a director, Jiang Wenbin, reported multiple transactions on 08/18/2025 relating to Restricted Stock Units (RSUs) that vested. Several RSU awards converted into shares: 6,758; 11,781; 22,100; and 29,002 RSUs were reported as vested and credited as common stock. To satisfy tax withholding on the vesting, the issuer withheld and surrendered shares in amounts of 1,646; 2,869; 5,382; and 7,062 at an indicated price of $4.06 per share. After these transactions, the filing shows beneficial ownership tallies following each line, with reported direct ownership figures such as 5,321,479 shares following the largest aggregation. The Form 4 was signed by an attorney-in-fact on behalf of the reporting person.

Positive

• Reporting person holds both President/CEO and Director roles, indicating alignment of management and board interests as disclosed
• RSU vesting reflects ongoing executive compensation/retention mechanisms with multiple tranches converting to common stock

Negative

• Shares were withheld and surrendered to satisfy tax obligations (1,646; 2,869; 5,382; 7,062 shares) which reduces net share increases to the reporting person
• Filing does not show open-market purchases that would increase insider ownership beyond vesting

Insights

Corporate Governance Expert

TL;DR: Routine executive equity vesting and share-withholding for taxes; no sale or acquisition for cash beyond withholding.

The filing documents scheduled vesting of multiple RSU awards for the President and CEO who is also a director, converting RSUs into common stock on 08/18/2025. The transactions include share withholding to satisfy tax obligations at $4.06 per share for specified lots. This is a standard compensation-related disclosure rather than a market-driven buy/sell signal. Reported post-transaction beneficial ownership levels are provided, indicating continued significant direct ownership by the reporting person.

Securities Analyst

TL;DR: Material only as insider compensation reporting; no cash sales or new purchases beyond tax-withholding reported.

The data shows conversion of RSUs into shares in several tranches and corresponding surrender of shares to cover withholding. The withholding was executed at $4.06 per share for the disclosed withheld amounts. There are no open-market purchase or sale transactions reported (no proceeds noted), so immediate market-impact implications are limited. This disclosure informs stakeholders about executive equity dilution and insider ownership levels.

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)
08/18/2025

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	08/18/2025		M		6,758	A	(1)	5,268,493	D
Common Stock	08/18/2025		F		1,646(2)	D	$4.06	5,266,847	D
Common Stock	08/18/2025		M		11,781	A	(1)	5,278,628	D
Common Stock	08/18/2025		F		2,869(2)	D	$4.06	5,275,759	D
Common Stock	08/18/2025		M		22,100	A	(1)	5,297,859	D
Common Stock	08/18/2025		F		5,382(2)	D	$4.06	5,292,477	D
Common Stock	08/18/2025		M		29,002	A	(1)	5,321,479	D
Common Stock	08/18/2025		F		7,062(2)	D	$4.06	5,314,417	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)	08/18/2025		M			6,758	(3)	(3)	Common Stock	6,758	$0	11,272	D
Restricted Stock Units	(1)	08/18/2025		M			11,781	(4)	(4)	Common Stock	11,781	$0	74,618	D
Restricted Stock Units	(1)	08/18/2025		M			22,100	(5)	(5)	Common Stock	22,100	$0	228,373	D
Restricted Stock Units	(1)	08/18/2025		M			29,002	(6)	(6)	Common Stock	29,002	$0	415,701	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 August 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	08/20/2025
	** 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 transactions did CTKB insider Jiang Wenbin report on 08/18/2025?

The filing reports multiple RSU vesting events that converted to common stock in amounts of 6,758; 11,781; 22,100; and 29,002 RSUs on 08/18/2025.

Were any shares sold by the insider in this Form 4 for CTKB?

No open-market sales are reported in this Form 4; only shares were withheld and surrendered to satisfy tax withholding on vested RSUs.

How many shares were withheld for taxes and at what price?

The issuer withheld 1,646; 2,869; 5,382; and 7,062 shares to satisfy tax obligations, with the withholding transactions disclosed at $4.06 per share.

What is the reporting person’s role at Cytek Biosciences (CTKB)?

The reporting person, Jiang Wenbin, is disclosed as President and CEO and as a Director of Cytek Biosciences.

Do the transactions change the insider’s beneficial ownership substantially?

The Form 4 lists post-transaction beneficial ownership figures after each line (for example 5,321,479 shares after one aggregation), indicating continued significant direct ownership; no material reduction from sales is shown.