What are Valerie Barnett’s Cytek Biosciences (CTKB) common share holdings after these transactions?

After the reported RSU exercises and tax withholding, Valerie Barnett directly held 136,009 shares of Cytek Biosciences common stock. This post-transaction balance reflects her ongoing equity stake as chief legal officer following the May 18, 2026 compensation events.

Cytek Biosciences (CTKB) CLO gains shares after RSU vesting

Filing Impact

(Neutral)

Filing Sentiment

(Neutral)

Form Type

Rhea-AI Filing Summary

Cytek Biosciences, Inc.’s chief legal officer Valerie Barnett reported routine equity compensation activity. On May 18, 2026, she exercised 24,295 Restricted Stock Units into common shares and had 8,719 shares withheld at $3.55 per share to cover tax obligations.

These tax-withholding dispositions were not open-market sales. After the transactions, she directly held 136,009 shares of common stock and continued to hold 12,280 Restricted Stock Units, reflecting ongoing equity-based compensation rather than discretionary trading.

Insider Trade Summary

24,295 shares exercised/converted

Mixed 12 txns

Insider Barnett Valerie

Role CHIEF LEGAL OFFICER

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units	2,454	$0.00	--
Exercise	Restricted Stock Units	5,156	$0.00	--
Exercise	Restricted Stock Units	7,250	$0.00	--
Exercise	Restricted Stock Units	9,435	$0.00	--
Exercise	Common Stock	2,454	$0.00	--
Tax Withholding	Common Stock	881	$3.55	$3K
Exercise	Common Stock	5,156	$0.00	--
Tax Withholding	Common Stock	1,850	$3.55	$7K
Exercise	Common Stock	7,250	$0.00	--
Tax Withholding	Common Stock	2,602	$3.55	$9K
Exercise	Common Stock	9,435	$0.00	--
Tax Withholding	Common Stock	3,386	$3.55	$12K

Holdings After Transaction: Restricted Stock Units — 12,280 shares (Direct, null); Common Stock — 136,890 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 exercised: 24,295 shares Shares withheld for taxes: 8,719 shares Tax withholding price: $3.55 per share +2 more

5 metrics

RSUs exercised 24,295 shares Restricted Stock Units converted to common stock on May 18, 2026

Shares withheld for taxes 8,719 shares Tax withholding dispositions at $3.55 per share on May 18, 2026

Tax withholding price $3.55 per share Value used for shares surrendered to satisfy tax obligations

Common shares held after 136,009 shares Direct Cytek Biosciences common stock holdings after transactions

Remaining RSU holdings 12,280 RSUs Restricted Stock Units remaining after the reported vesting events

Key Terms

Restricted Stock Unit, tax withholding obligations, derivative exercise/conversion, Payment of exercise price or tax liability by delivering securities, +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

"to satisfy tax withholding obligations that arose in connection with the vesting of the RSU Award"

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""

vest over 4 years financial

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

Form 4 Insider Transactions: What Each Field Means →

05/20/2026 - 05:45 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^*

Barnett Valerie

(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)

	Director	10% Owner
X	Officer (give title below)	Other (specify below)
	CHIEF LEGAL 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		2,454	A	⁽¹⁾	136,890	D
Common Stock	05/18/2026		F		881⁽²⁾	D	$3.55	136,009	D
Common Stock	05/18/2026		M		5,156	A	⁽¹⁾	141,165	D
Common Stock	05/18/2026		F		1,850⁽²⁾	D	$3.55	139,315	D
Common Stock	05/18/2026		M		7,250	A	⁽¹⁾	146,565	D
Common Stock	05/18/2026		F		2,602⁽²⁾	D	$3.55	143,963	D
Common Stock	05/18/2026		M		9,435	A	⁽¹⁾	153,398	D
Common Stock	05/18/2026		F		3,386⁽²⁾	D	$3.55	150,012	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			2,454	⁽³⁾	⁽³⁾	Common Stock	2,454	$0	12,280	D
Restricted Stock Units	⁽¹⁾	05/18/2026		M			5,156	⁽⁴⁾	⁽⁴⁾	Common Stock	5,156	$0	56,728	D
Restricted Stock Units	⁽¹⁾	05/18/2026		M			7,250	⁽⁵⁾	⁽⁵⁾	Common Stock	7,250	$0	123,262	D
Restricted Stock Units	⁽¹⁾	05/18/2026		M			9,435	⁽⁶⁾	⁽⁶⁾	Common Stock	9,435	$0	217,018	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	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) insider Valerie Barnett report on this Form 4?

Valerie Barnett, Cytek Biosciences’ chief legal officer, reported exercising 24,295 Restricted Stock Units into common shares. She also had 8,719 shares withheld to satisfy tax obligations. These are compensation-related transactions rather than discretionary open-market trading.

Did Cytek Biosciences (CTKB) insider Valerie Barnett sell shares on the market?

The Form 4 shows no open-market sales by Valerie Barnett. Instead, 8,719 shares were withheld and surrendered to Cytek Biosciences at $3.55 per share to cover tax liabilities arising from RSU vesting, a standard, non-market mechanism.

How many Cytek Biosciences (CTKB) RSUs did Valerie Barnett exercise and what remains?

Barnett exercised 24,295 Restricted Stock Units into Cytek Biosciences common shares on May 18, 2026. Following these exercises, she continued to hold 12,280 Restricted Stock Units, which represent additional contingent rights to receive common stock under the company’s equity program.

How are the Cytek Biosciences (CTKB) RSU awards structured for vesting?

The RSU awards vest over four years using a detailed schedule. Portions equal to 2/48, 3/48, and 4/48 of the total RSUs vest on specified dates each May 18, August 18, November 18, and March 10, respectively, until the awards are fully vested.