CTKB Insider Filing: Yan Ming RSU Vesting and Tax Withholding Details

Rhea-AI Filing Summary

Cytek Biosciences director and Chief Technology Officer Yan Ming reported multiple Form 4 transactions on 08/18/2025 related to the vesting of Restricted Stock Units (RSUs). The filings show vesting events that increased Mr. Yan's direct beneficial ownership to 6,058,887 shares of common stock after the reported transactions. Several tranches vested on 08/18/2025 totaling 20,?231 RSUs (1,981 + 7,363 + 5,525 + 6,162) and certain shares were withheld to satisfy tax withholding obligations at a price of $4.06 per share for the withheld amounts. The RSU awards follow multi‑year vesting schedules described in the explanation, with quarterly or annual vesting components.

Positive

• Insider beneficial ownership reported at 6,058,887 shares, indicating significant alignment with shareholders
• RSU vesting schedules are clearly disclosed with specific vesting cadence for transparency

Negative

• Shares were withheld to satisfy tax obligations (various small amounts), reducing the net increase in outstanding shares received by the insider

Insights

Financial Analyst

TL;DR: Routine RSU vesting and tax-withholding transactions increased direct holdings to ~6.06M shares; no sales or option exercises reported.

The Form 4 reflects customary equity compensation mechanics: multiple RSU tranches vested on 08/18/2025, increasing direct ownership to 6,058,887 shares. Portions of vested shares were surrendered to the issuer to satisfy tax withholding, reported at $4.06 per share. These are non‑derivative, non‑sale events (transaction codes M and F) and do not indicate monetization or change in control. Impact on float and dilution is incremental and tied to planned compensation schedules rather than discretionary trading.

Corporate Governance Expert

TL;DR: Disclosure is standard for an officer/director receiving RSU vesting; documentation of vesting schedule and withholding is clear and complete.

The filing properly discloses the nature of the awards, vesting cadence, and tax withholding actions. Vesting schedules are specified for each RSU grant, including quarterly and annual tranches, which supports transparency around insider accumulation. There is no indication of Rule 10b5-1 trading plan usage or unusual related‑party transactions. From a governance perspective, these are routine equity compensation disclosures.

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^*

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)
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		1,981	A	(1)	6,044,107	D
Common Stock	08/18/2025		F		588(2)	D	$4.06	6,043,519	D
Common Stock	08/18/2025		M		7,363	A	(1)	6,050,882	D
Common Stock	08/18/2025		F		2,184(2)	D	$4.06	6,048,698	D
Common Stock	08/18/2025		M		5,525	A	(1)	6,054,223	D
Common Stock	08/18/2025		F		1,498(2)	D	$4.06	6,052,725	D
Common Stock	08/18/2025		M		6,162	A	(1)	6,058,887	D
Common Stock	08/18/2025		F		1,468(2)	D	$4.06	6,057,419	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			1,981	(3)	(3)	Common Stock	1,981	$0	3,313	D
Restricted Stock Units	(1)	08/18/2025		M			7,363	(4)	(4)	Common Stock	7,363	$0	46,640	D
Restricted Stock Units	(1)	08/18/2025		M			5,525	(5)	(5)	Common Stock	5,525	$0	57,094	D
Restricted Stock Units	(1)	08/18/2025		M			6,162	(6)	(6)	Common Stock	6,162	$0	88,337	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.
* 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 transactions did Yan Ming report on Form 4 for CTKB?

The Form 4 reports multiple RSU vesting events on 08/18/2025, with certain vested shares withheld to satisfy tax obligations at $4.06 per withheld share.

How many shares does Yan Ming beneficially own after these transactions?

Following the reported transactions, Yan Ming beneficially owns 6,058,887 shares of Cytek Biosciences common stock.

Were any shares sold by Yan Ming in this filing?

No sales are reported; the transactions are vesting of RSUs (transaction code M) and shares withheld for tax (transaction code F).

Do the filings indicate a trading plan under Rule 10b5-1?

The Form 4 does not indicate that the transactions were made pursuant to a Rule 10b5-1 trading plan.

What is the nature of the reported RSU awards?

Each RSU represents a contingent right to receive one share of common stock; vesting schedules vary by grant but extend over four years with specified quarterly or annual vesting increments.