Cytek director awarded 55,555 RSUs, 29,835 options

Cytek Biosciences director Glenn P. Muir reported equity awards that increase his potential ownership in the company.

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Form Type

Rhea-AI Filing Summary

Cytek Biosciences director Glenn P. Muir reported equity awards that increase his potential ownership in the company. He received a stock option for 29,835 shares of common stock at an exercise price of $4.05 per share, expiring on June 10, 2036. He also received 55,555 restricted stock units, each representing one share of common stock.

The option vests in equal monthly installments over three years following the June 10, 2026 grant date. The restricted stock units vest in tranches between August 18, 2026 and August 18, 2027 based on a detailed schedule, tying full ownership to continued service.

Insider Trade Summary

Grant/Award: 85,390 shares

Grant/Award 2 txns

Insider MUIR GLENN P

Role Director

Type	Security	Shares	Price	Value
Grant/Award	Restricted Stock Units	55,555	$0.00	$0.00
Grant/Award	Director Stock Option (right to buy)	29,835	$0.00	$0.00

Holdings After Transaction: Restricted Stock Units — 55,555 contracts (Direct); Director Stock Option (right to buy) — 29,835 contracts (Direct)

Footnotes (3)

F1. Each Restricted Stock Unit (the "RSU Award") represents a contingent right to receive one share of the Issuer's common stock.
F2. 2/36 of the total shares subject to the RSU Award shall vest on August 18, 2026; 3/36 of the total shares subject to the RSU Award shall vest on November 18, 2026 and each November 18 thereafter; 4/36 of the total shares underlying the RSU Award shall vest on March 10, 2027 and each March 10 thereafter; 3/36 of the total shares underlying the RSU Award vesting shall vest on May 18, 2027 and each May 18 thereafter; and 3/36 of the total shares underlying the RSU Award shall vest on August 18, 2027 and each August 18 thereafter, until fully vested.
F3. 1/36 of the total shares subject to the option shall vest monthly over 3 years following the grant date of June 10, 2026.

Key Figures

Director stock option grant: 29,835 shares Option exercise price: $4.05 per share Option expiration: June 10, 2036 +3 more

6 metrics

Director stock option grant 29,835 shares Director Stock Option granted June 10, 2026

Option exercise price $4.05 per share Exercise price for 29,835-share director option

Option expiration June 10, 2036 Expiration date of director stock option

RSU grant size 55,555 units Restricted Stock Units granted June 10, 2026

Option vesting rate 1/36 monthly Option vests monthly over 3 years after June 10, 2026

RSU initial vesting 2/36 of grant RSUs vest 2/36 on August 18, 2026

Key Terms

Restricted Stock Units, Director Stock Option (right to buy), RSU Award, vest, +1 more

5 terms

Restricted Stock Units financial

"The reporting person acquired 55,555 "Restricted Stock Units" as a derivative security."

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.

Director Stock Option (right to buy) financial

"Security title is listed as "Director Stock Option (right to buy)" with common stock underlying."

RSU Award financial

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

vest financial

"2/36 of the total shares subject to the RSU Award shall vest on August 18, 2026."

A vest is the process by which an employee earns the right to receive certain benefits or ownership interests, such as stock or retirement funds, over time. It’s similar to earning a reward gradually, ensuring that the benefit becomes fully yours only after a set period or meeting specific conditions. This makes it important for investors because it determines when they can actually claim or use those benefits.

exercise price financial

"The option has a conversion or exercise price of 4.0500 per share."

The exercise price is the fixed amount at which you can buy or sell an asset, like a stock, when using an options contract. It matters because it helps determine whether exercising the option will be profitable or not, depending on the current market price. Think of it as the set price you agree on today to buy or sell later.

FAQ

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

What insider transactions did Cytek Biosciences (CTKB) disclose for Glenn P. Muir?

Cytek Biosciences disclosed that director Glenn P. Muir received a stock option for 29,835 shares and 55,555 restricted stock units. Both awards are compensation grants, not open-market trades, and will convert into common stock only as they vest or are exercised over time.

How many Cytek Biosciences (CTKB) options were granted to director Glenn P. Muir?

Glenn P. Muir was granted a director stock option covering 29,835 shares of Cytek Biosciences common stock. The option has an exercise price of $4.05 per share and vests in 36 equal monthly installments over three years beginning after the June 10, 2026 grant date.

What are the details of the Cytek Biosciences (CTKB) RSU grant to Glenn P. Muir?

Muir received 55,555 restricted stock units, each representing one share of Cytek Biosciences common stock. The RSUs vest in multiple tranches between August 18, 2026 and August 18, 2027, with different fractions of the grant vesting on specified quarterly and annual dates during that period.

Are Glenn P. Muir’s Cytek Biosciences (CTKB) transactions open-market buys or compensation awards?

The reported transactions are compensation awards, not open-market purchases. Both are coded as grants or awards, with a zero-dollar transaction price. One award is a stock option with a $4.05 exercise price; the other is an RSU grant settling in common shares as it vests.

When do Glenn P. Muir’s Cytek Biosciences (CTKB) stock options and RSUs vest?

The stock option vests at a rate of 1/36 of the total shares monthly over three years following June 10, 2026. The RSUs vest in scheduled fractions on August 18, November 18, March 10, May 18, and August 18 dates between 2026 and 2027, until fully vested.

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

Form 4 Insider Transactions: What Each Field Means →

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Accepted by SEC EDGAR 06/12/2026 - 07:31 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^*

MUIR GLENN P

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/10/2026

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)

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⁾	06/10/2026		A		55,555		⁽²⁾	⁽²⁾	Common Stock	55,555	$0	55,555	D
Director Stock Option (right to buy)	$4.05	06/10/2026		A		29,835		⁽³⁾	06/10/2036	Common Stock	29,835	$0	29,835	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. 2/36 of the total shares subject to the RSU Award shall vest on August 18, 2026; 3/36 of the total shares subject to the RSU Award shall vest on November 18, 2026 and each November 18 thereafter; 4/36 of the total shares underlying the RSU Award shall vest on March 10, 2027 and each March 10 thereafter; 3/36 of the total shares underlying the RSU Award vesting shall vest on May 18, 2027 and each May 18 thereafter; and 3/36 of the total shares underlying the RSU Award shall vest on August 18, 2027 and each August 18 thereafter, until fully vested.

3. 1/36 of the total shares subject to the option shall vest monthly over 3 years following the grant date of June 10, 2026.

	/s/ Valerie Barnett, Attorney-in-Fact	06/12/2026
	** 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

Cytek director awarded 55,555 RSUs, 29,835 options

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