Cytek (CTKB) Form 4: Executive RSUs Vesting and Withheld Shares Reported

Rhea-AI Filing Summary

William D. McCombe, Chief Financial Officer and Director of Cytek Biosciences, Inc. (CTKB), reported changes in beneficial ownership related to vesting of restricted stock units on 08/18/2025.

The filing shows two RSU vesting events recorded as acquisitions of 6,320 and 13,051 RSUs (each RSU convertible into one share). To satisfy tax withholding on the vesting, the issuer withheld 2,462 and 5,084 shares at a per-share price of $4.06. Post-transaction ownership figures reported in the form include multiple balances (for common stock and underlying derivative holdings), with derivative share totals of 6,320 and 13,051 underlying shares and aggregate beneficial ownership figures shown in the filing. The RSUs vest over four years on a specified schedule described in the explanations. The form was signed by an attorney-in-fact on 08/20/2025.

Positive

• RSU vesting disclosed, showing alignment of executive compensation with long-term retention
• No open-market sales reported other than shares withheld to satisfy tax obligations

Negative

• Shares withheld for tax withholding reduced the net increase in beneficial ownership
• Filing shows standard dilution potential as multiple RSU tranches remain scheduled to vest

Insights

Financial Analyst

TL;DR: Routine executive equity vesting and tax-withholding; no sales beyond withholding, so limited immediate market impact.

The Form 4 documents standard compensation vesting for the CFO with two RSU vesting events that increased his beneficially owned shares while triggering share-withholding to satisfy taxes at $4.06 per share. This is a non-dispositive event for investors: it does not indicate a cash sale or material disposition beyond withholding, and reported post-transaction holdings remain concentrated as shown. The filing provides clear vesting schedules and exact withheld-share counts, allowing precise tracking of future share releases.

Corporate Governance Expert

TL;DR: Vesting of executive RSUs aligns compensation with retention; disclosure is timely and complies with Section 16 reporting.

The submission discloses the mechanics of RSU vesting and tax withholding consistent with standard equity compensation practices. The detailed vesting timetable and number of shares withheld for taxes support transparency around insider incentives and dilution timing. There is no indication of unexpected dispositions or governance concerns in this 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^*

McCombe William D.

(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 Financial Officer

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		6,320	A	(1)	62,066	D
Common Stock	08/18/2025		F		2,462(2)	D	$4.06	59,604	D
Common Stock	08/18/2025		M		13,051	A	(1)	72,655	D
Common Stock	08/18/2025		F		5,084(2)	D	$4.06	67,571	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			6,320	(3)	(3)	Common Stock	6,320	$0	69,529	D
Restricted Stock Units	(1)	08/18/2025		M			13,051	(4)	(4)	Common Stock	13,051	$0	187,065	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 over 4 years with 12/48 of the total shares underlying the RSU Award vesting on May 18, 2025; 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 3/48 of the total shares underlying the RSU Award vesting on March 10, 2026 and each March 10 thereafter; and 3/48 of the total shares underlying the RSU Award vesting on May 18, 2026 and each May 18 thereafter.

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, 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.
* 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.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What did CTKB insider William D. McCombe report on the Form 4?

He reported the vesting of 6,320 and 13,051 restricted stock units on 08/18/2025 and related withheld shares for taxes.

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

The issuer withheld 2,462 and 5,084 shares on 08/18/2025 at a per-share price of $4.06.

What is William McCombe's relationship to CTKB?

The form lists him as a Director and the company's Chief Financial Officer.

Does the Form 4 show any open-market sales by the reporting person?

No open-market sales are reported; dispositions shown relate to share withholding to satisfy tax obligations.

What is the vesting schedule described for the RSUs?

The RSUs vest over four years with specific fractional vesting on May, August, November, and March dates as detailed in the filing.