Cytek director converts 2,181 RSUs into shares

Cytek Biosciences, Inc. (CTKB) reported that director Michael Holder exercised restricted stock units into common stock.

Rhea-AI Filing Summary

Cytek Biosciences, Inc. (CTKB) reported that director Michael Holder exercised restricted stock units into common stock. On August 18, 2026, 2,181 Restricted Stock Units converted into 2,181 shares of common stock, increasing his directly held common shares to 62,875 and reducing his Restricted Stock Units to 7,276. Each RSU represents a contingent right to receive one share of common stock, with the underlying RSU award vesting in scheduled tranches through at least August 18, 2025 as described in the vesting footnote.

Insider Trade Summary

2,181 shares exercised/converted

Exercise 2 txns

Insider Holder Michael

Role Director

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units F1, F2	2,181	$0.00	$0.00
Exercise	Common Stock F1	2,181	--	--

Holdings After Transaction: Restricted Stock Units — 7,276 contracts (Direct); Common Stock — 62,875 shares (Direct)

Footnotes (2)

1. F1. Each Restricted Stock Unit (the "RSU Award") represents a contingent right to receive one share of the Issuer's common stock.
2. F2. The shares underlying the RSU Award shall vest over 3 years, with 2/36 of the total shares underlying the RSU Award vesting on August 18, 2024; 3/36 of the total shares underlying the RSU Award vesting on November 18, 2024 and each November 18 thereafter; 4/36 of the total shares underlying the RSU Award vesting on March 10, 2025 and each March 10 thereafter; 2/36 of the total shares underlying the RSU Award vesting on May 18, 2025 and each May 18 thereafter; and 3/36 of the total shares underlying the RSU Award vesting on August 18, 2025 and each August 18 thereafter.

Key Figures

RSUs converted: 2,181 Restricted Stock Units Common stock holdings after transaction: 62,875 shares Restricted Stock Units remaining: 7,276 Restricted Stock Units +3 more

6 metrics

RSUs converted 2,181 Restricted Stock Units Converted into common stock on August 18, 2026

Common stock holdings after transaction 62,875 shares Directly held by Michael Holder after the August 18, 2026 transaction

Restricted Stock Units remaining 7,276 Restricted Stock Units RSU balance following the August 18, 2026 conversion

RSU vesting term 3 years Stated vesting period for the RSU Award

Initial vesting fraction on August 18, 2024 2/36 of total RSU shares First vesting tranche of the RSU Award

Subsequent November vesting fraction 3/36 of total RSU shares Vests on November 18, 2024 and each November 18 thereafter

Key Terms

Restricted Stock Units, RSU Award, contingent right, vesting

4 terms

Restricted Stock Units financial

"Each Restricted Stock Unit (the "RSU Award") represents a contingent right"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

RSU Award financial

"Each Restricted Stock Unit (the "RSU Award") represents a contingent right"

contingent right financial

"represents a contingent right to receive one share of the Issuer's common stock"

vesting financial

"The shares underlying the RSU Award shall vest over 3 years"

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.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did CTKB director Michael Holder report in this Form 4?

Michael Holder reported the exercise of 2,181 Restricted Stock Units, which converted into 2,181 shares of Cytek Biosciences, Inc. common stock on August 18, 2026. This increased his directly held common stock position and reduced his unvested Restricted Stock Units.

How many CTKB common shares does Michael Holder own after this transaction?

After the reported transaction, Michael Holder directly owns 62,875 shares of common stock of Cytek Biosciences, Inc., as stated in the post-transaction holdings for the non-derivative common stock line.

How many Restricted Stock Units does Michael Holder hold after the CTKB Form 4 transaction?

Following the August 18, 2026 exercise, Michael Holder holds 7,276 Restricted Stock Units. These RSUs each represent a contingent right to receive one share of Cytek Biosciences, Inc. common stock, subject to the vesting schedule described in the footnotes.

What is the vesting structure of Michael Holder’s CTKB RSU Award?

The RSU Award vests over 3 years: 2/36 of total shares on August 18, 2024; 3/36 on November 18, 2024 and each November 18 thereafter; 4/36 on March 10, 2025 and each March 10 thereafter; 2/36 on May 18, 2025 and each May 18 thereafter; and 3/36 on August 18, 2025 and each August 18 thereafter.

What does each CTKB Restricted Stock Unit represent for Michael Holder?

Each Restricted Stock Unit (the RSU Award) represents a contingent right to receive one share of Cytek Biosciences, Inc. common stock, subject to the time-based vesting schedule outlined in the award’s footnote.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 08/20/2026 - 04:28 PM EDT Accepted by SEC EDGAR 08/20/2026 - 04:28 PM EDT Learn about SEC filing dates

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^*

Holder Michael

(Last) (First) (Middle)

C/O CYTEK BIOSCIENCES, INC.

47215 LAKEVIEW BLVD.

(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
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/18/2026

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/18/2026		M		2,181	A	(1)	62,875	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)	08/18/2026		M			2,181	(2)	(2)	Common Stock	2,181	$0	7,276	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. The shares underlying the RSU Award shall vest over 3 years, with 2/36 of the total shares underlying the RSU Award vesting on August 18, 2024; 3/36 of the total shares underlying the RSU Award vesting on November 18, 2024 and each November 18 thereafter; 4/36 of the total shares underlying the RSU Award vesting on March 10, 2025 and each March 10 thereafter; 2/36 of the total shares underlying the RSU Award vesting on May 18, 2025 and each May 18 thereafter; and 3/36 of the total shares underlying the RSU Award vesting on August 18, 2025 and each August 18 thereafter.

	/s/ Gordon Ho, Attorney-in-Fact	08/20/2026
	** 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)