Were Yan Ming’s Cytek (CTKB) share dispositions open-market sales?

No. The dispositions are labeled with transaction code “F” and described as payments of tax liabilities by delivering securities. Footnotes state the shares were withheld and surrendered to the issuer, not sold through open-market transactions.

Cytek Biosciences (CTKB) CTO vests RSUs, holds 4,919,617 shares

Q: How many Cytek (CTKB) shares did Yan Ming acquire through RSU vesting?

Yan Ming acquired 22,179 shares of Cytek common stock through the exercise and settlement of restricted stock units. Each RSU represents a contingent right to receive one share of common stock upon vesting under the award terms.

Q: How many Cytek (CTKB) shares were withheld for Yan Ming’s taxes and at what price?

A total of 5,532 shares of Cytek common stock were withheld and surrendered to the issuer to satisfy tax withholding obligations, at a price of $3.55 per share , according to the reported Form 4 transaction details.

Filing Impact

(Neutral)

Filing Sentiment

(Neutral)

Form Type

Rhea-AI Filing Summary

Cytek Biosciences, Inc. director and Chief Technology Officer Yan Ming reported routine equity compensation activity. On May 18, 2026, Ming exercised restricted stock units that converted into 22,179 shares of common stock in total. To cover tax obligations tied to these vestings, 5,532 shares of common stock were withheld and surrendered to the company at $3.55 per share, rather than sold on the open market. After these transactions, Ming directly owned 4,919,617 shares of Cytek common stock.

Insider Trade Summary

22,179 shares exercised/converted

Mixed 12 txns

Insider Yan Ming

Role CHIEF TECHNOLOGY OFFICER

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units	4,908	$0.00	--
Exercise	Restricted Stock Units	3,683	$0.00	--
Exercise	Restricted Stock Units	4,108	$0.00	--
Exercise	Restricted Stock Units	9,480	$0.00	--
Exercise	Common Stock	4,908	$0.00	--
Tax Withholding	Common Stock	1,224	$3.55	$4K
Exercise	Common Stock	3,683	$0.00	--
Tax Withholding	Common Stock	919	$3.55	$3K
Exercise	Common Stock	4,108	$0.00	--
Tax Withholding	Common Stock	1,025	$3.55	$4K
Exercise	Common Stock	9,480	$0.00	--
Tax Withholding	Common Stock	2,364	$3.55	$8K

Holdings After Transaction: Restricted Stock Units — 24,552 shares (Direct, null); Common Stock — 4,920,841 shares (Direct, null)

Footnotes (1)

Each Restricted Stock Unit (the "RSU Award") represents a contingent right to receive one share of the Issuer's common stock. Represents the number of shares withheld by and surrendered to the Issuer on May 18, 2026, to satisfy tax withholding obligations that arose in connection with the vesting of the RSU Award. 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. 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. 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. 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, 2026 and each May 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on August 18, 2026 and each August 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on November 18, 2026 and each November 18 thereafter; and 4/48 of the total shares underlying the RSU Award vesting on March 10, 2027 and each March 10 thereafter, until fully vested.

Key Figures

RSUs converted to common stock: 22,179 shares Shares withheld for taxes: 5,532 shares Tax withholding price: $3.55 per share +3 more

6 metrics

RSUs converted to common stock 22,179 shares Total derivative exercises (M code) on May 18, 2026

Shares withheld for taxes 5,532 shares Tax-withholding dispositions (F code) at $3.55 per share

Tax withholding price $3.55 per share Value used for shares surrendered to issuer

Shares held after transactions 4,919,617 shares Direct common stock ownership after May 18, 2026 activity

Exercise transactions count 4 transactions M-code derivative exercises reported in transactionSummary

Tax-withholding transactions count 4 transactions F-code dispositions for tax obligations

Key Terms

Restricted Stock Unit, tax withholding obligations, vesting, derivative exercise/conversion, +1 more

5 terms

Restricted Stock Unit financial

"Each Restricted Stock Unit (the "RSU Award") represents a contingent right to receive one share..."

A restricted stock unit is a promise from a company to give an employee shares of stock after certain conditions are met, like staying with the company for a set amount of time. It’s like earning a bonus that turns into company stock once you’ve proven your commitment, making it a way to motivate and reward employees.

tax withholding obligations financial

"shares withheld by and surrendered to the Issuer... to satisfy tax withholding obligations..."

vesting financial

"The shares subject to the RSU Award shall vest over 4 years with 2/48 of the total shares..."

Vesting is the process by which you earn full ownership of something, like company stock or a retirement benefit, over time. It’s like earning the right to keep a gift piece by piece the longer you stay with a company, making sure employees stay committed before they receive all the benefits.

derivative exercise/conversion financial

"transaction_action": "derivative exercise/conversion""

payment of exercise price or tax liability by delivering securities financial

"transaction_code_description": "Payment of exercise price or tax liability by delivering securities""

Form 4 Insider Transactions: What Each Field Means →

05/20/2026 - 05:56 PM

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

CALIFORNIA

94538

(City)

(State)

(Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/18/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	05/18/2026		M		4,908	A	⁽¹⁾	4,920,841	D
Common Stock	05/18/2026		F		1,224⁽²⁾	D	$3.55	4,919,617	D
Common Stock	05/18/2026		M		3,683	A	⁽¹⁾	4,923,300	D
Common Stock	05/18/2026		F		919⁽²⁾	D	$3.55	4,922,381	D
Common Stock	05/18/2026		M		4,108	A	⁽¹⁾	4,926,489	D
Common Stock	05/18/2026		F		1,025⁽²⁾	D	$3.55	4,925,464	D
Common Stock	05/18/2026		M		9,480	A	⁽¹⁾	4,934,944	D
Common Stock	05/18/2026		F		2,364⁽²⁾	D	$3.55	4,932,580	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Restricted Stock Units	⁽¹⁾	05/18/2026		M			4,908	⁽³⁾	⁽³⁾	Common Stock	4,908	$0	24,552	D
Restricted Stock Units	⁽¹⁾	05/18/2026		M			3,683	⁽⁴⁾	⁽⁴⁾	Common Stock	3,683	$0	40,520	D
Restricted Stock Units	⁽¹⁾	05/18/2026		M			4,108	⁽⁵⁾	⁽⁵⁾	Common Stock	4,108	$0	69,850	D
Restricted Stock Units	⁽¹⁾	05/18/2026		M			9,480	⁽⁶⁾	⁽⁶⁾	Common Stock	9,480	$0	218,055	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 May 18, 2026, 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 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.

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, 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.

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, 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.

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, 2026 and each May 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on August 18, 2026 and each August 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting on November 18, 2026 and each November 18 thereafter; and 4/48 of the total shares underlying the RSU Award vesting on March 10, 2027 and each March 10 thereafter, until fully vested.

	/s/ Valerie Barnett, Attorney-in-Fact	05/20/2026
	** 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.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR

FAQ

What did Cytek Biosciences (CTKB) CTO Yan Ming report in this Form 4?

Yan Ming reported vesting of restricted stock units that converted into Cytek common shares, along with related tax-withholding share dispositions. These transactions reflect routine equity compensation mechanics rather than open-market buying or selling activity.

How many Cytek (CTKB) shares did Yan Ming acquire through RSU vesting?

Yan Ming acquired 22,179 shares of Cytek common stock through the exercise and settlement of restricted stock units. Each RSU represents a contingent right to receive one share of common stock upon vesting under the award terms.

How many Cytek (CTKB) shares were withheld for Yan Ming’s taxes and at what price?

A total of 5,532 shares of Cytek common stock were withheld and surrendered to the issuer to satisfy tax withholding obligations, at a price of $3.55 per share, according to the reported Form 4 transaction details.

How many Cytek Biosciences (CTKB) shares does Yan Ming hold after these transactions?

Following the reported RSU exercises and tax-withholding share surrenders, Yan Ming directly owns 4,919,617 shares of Cytek Biosciences common stock, as disclosed in the post-transaction ownership fields in the Form 4 filing.

What do the RSU vesting schedules in Cytek (CTKB) CTO Yan Ming’s filing indicate?

Footnotes describe RSU awards vesting over four years on specific quarterly dates, in fractional portions such as 2/48, 3/48, and 4/48 of the total shares. This illustrates a structured, time-based equity compensation program for the CTO role.