STOCK TITAN
  1. Home
  2. Sec-filings
  3. CTKB
  4. [Form 4] Cytek Biosciences, Inc. Insider Trading Activity

Cytek Biosciences (NASDAQ: CTKB) SVP granted options, RSUs and sees RSU vesting

Filing Impact
(Neutral)
Filing Sentiment
(Neutral)
Form Type
4

Rhea-AI Filing Summary

Cytek Biosciences SVP Philippe Busque reported equity compensation and vesting activity. On March 10, 2026 he received an employee stock option for 70,665 shares of common stock at an exercise price of $4.23 per share, vesting monthly over four years. He was also granted 133,226 restricted stock units, each representing one share of common stock, scheduled to vest over four years under specified annual dates.

On the same date, several existing RSU awards vested, leading to the issuance of 9,828 shares of common stock through derivative exercises, while 3,043 shares were withheld by the company at $4.23 per share to cover tax obligations. Following these transactions, Busque directly held 35,687 shares of common stock.

Positive

  • None.

Negative

  • None.

Insights

Routine equity grants and RSU vesting for Cytek SVP.

The transactions for Cytek Biosciences SVP Philippe Busque are primarily stock-based compensation. He received an option on 70,665 shares at an exercise price of $4.23 and 133,226 new RSUs, all vesting over four years via detailed schedules.

Existing RSU awards partially vested, converting 9,828 units into common stock, with 3,043 shares withheld to satisfy tax obligations. No open‑market purchases or sales occurred, and Busque ended with 35,687 common shares directly held. Overall, these actions appear as standard executive compensation and vesting rather than a directional bet on the stock.

Insider Busque Philippe
Role SVP, GLOBAL SALES AND SERVICES
Type Security Shares Price Value
Grant/Award Employee Stock Option (right to buy) 70,665 $0.00 --
Grant/Award Restricted Stock Units 133,226 $0.00 --
Exercise Restricted Stock Units 2,049 $0.00 --
Exercise Restricted Stock Units 2,946 $0.00 --
Exercise Restricted Stock Units 4,833 $0.00 --
Exercise Common Stock 2,049 $0.00 --
Tax Withholding Common Stock 635 $4.23 $3K
Exercise Common Stock 2,946 $0.00 --
Tax Withholding Common Stock 912 $4.23 $4K
Exercise Common Stock 4,833 $0.00 --
Tax Withholding Common Stock 1,496 $4.23 $6K
Holdings After Transaction: Employee Stock Option (right to buy) — 70,665 shares (Direct); Restricted Stock Units — 133,226 shares (Direct); Common Stock — 30,951 shares (Direct)
Footnotes (1)
  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 March 10, 2026, to satisfy tax withholding obligations that arose in connection with the vesting of the RSU Award. The shares subject to the stock option shall vest over 4 years with 1/48 of the total shares underlying the stock option vesting on April 10, 2026 and each month 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 August 18, 2026 and each August 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting 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. The shares subject to the RSU Award shall vest over four years with 13/48 of the total shares underlying the RSU Award vesting on May 18, 2024; 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; 4/48 of the total shares underlying the RSU Award vesting on March 10, 2025 and each March 10 thereafter; and 2/48 of the total shares underlying the RSU Award vesting on May 18, 2025 and each May 18 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, 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.
Form 4 Insider Transactions: What Each Field Means →
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*
Busque Philippe
(Last) (First) (Middle)
C/O CYTEK BIOSCIENCES, INC.
47215 LAKEVIEW BLVD.
(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)
Director 10% Owner
X Officer (give title below) Other (specify below)
SVP, GLOBAL SALES AND SERVICES
3. Date of Earliest Transaction (Month/Day/Year)
03/10/2026
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 03/10/2026 M 2,049 A (1) 30,951 D
Common Stock 03/10/2026 F 635(2) D $4.23 30,316 D
Common Stock 03/10/2026 M 2,946 A (1) 33,262 D
Common Stock 03/10/2026 F 912(2) D $4.23 32,350 D
Common Stock 03/10/2026 M 4,833 A (1) 37,183 D
Common Stock 03/10/2026 F 1,496(2) D $4.23 35,687 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
Employee Stock Option (right to buy) $4.23 03/10/2026 A 70,665 (3) 03/09/2036 Common Stock 70,665 $0 70,665 D
Restricted Stock Units (1) 03/10/2026 A 133,226 (4) (4) Common Stock 133,226 $0 133,226 D
Restricted Stock Units (1) 03/10/2026 M 2,049 (5) (5) Common Stock 2,049 $0 6,665 D
Restricted Stock Units (1) 03/10/2026 M 2,946 (6) (6) Common Stock 2,946 $0 17,682 D
Restricted Stock Units (1) 03/10/2026 M 4,833 (7) (7) Common Stock 4,833 $0 43,505 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 March 10, 2026, to satisfy tax withholding obligations that arose in connection with the vesting of the RSU Award.
3. The shares subject to the stock option shall vest over 4 years with 1/48 of the total shares underlying the stock option vesting on April 10, 2026 and each month 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, 2026 and each May 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting August 18, 2026 and each August 18 thereafter; 3/48 of the total shares underlying the RSU Award vesting 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.
5. The shares subject to the RSU Award shall vest over four years with 13/48 of the total shares underlying the RSU Award vesting on May 18, 2024; 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; 4/48 of the total shares underlying the RSU Award vesting on March 10, 2025 and each March 10 thereafter; and 2/48 of the total shares underlying the RSU Award vesting on May 18, 2025 and each May 18 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, 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.
7. 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 03/12/2026
** 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.

Source: View Original Filing on SEC EDGAR

FAQ

What did Cytek Biosciences (CTKB) SVP Philippe Busque receive in this Form 4 filing?

Philippe Busque received an employee stock option for 70,665 shares at a $4.23 exercise price and 133,226 restricted stock units. Both awards are scheduled to vest over four years according to specified vesting dates described in the filing’s footnotes.

How many Cytek Biosciences (CTKB) RSUs vested for Philippe Busque on March 10, 2026?

On March 10, 2026, RSU vesting converted a total of 9,828 restricted stock units into common shares for Philippe Busque. These came from multiple RSU awards that vested according to previously established four‑year vesting schedules described in the filing’s detailed footnotes.

Were any Cytek Biosciences (CTKB) shares sold on the market in this Form 4?

No open-market sales were reported. The only share disposals were 3,043 shares of common stock withheld by Cytek Biosciences at $4.23 per share to satisfy tax withholding obligations triggered by the vesting of restricted stock unit awards.

How many Cytek Biosciences (CTKB) common shares does Philippe Busque hold after these transactions?

After the reported grants, vesting, and tax withholding, Philippe Busque directly holds 35,687 shares of Cytek Biosciences common stock. This figure reflects his position immediately following the March 10, 2026 equity compensation and RSU vesting activity disclosed in the Form 4.

What are the key terms of Philippe Busque’s new Cytek (CTKB) stock option grant?

The new employee stock option covers 70,665 shares of Cytek common stock with a $4.23 exercise price. It vests over four years, with 1/48 of the shares vesting each month starting April 10, 2026, until the option is fully vested by expiration.

How do the new RSU awards for Cytek Biosciences (CTKB) SVP vest over time?

The 133,226 new RSUs for Philippe Busque vest over four years on specified annual dates. Portions vest each May 18, August 18, November 18, and March 10, with varying 2/48, 3/48, 4/48, or 13/48 fractions, until the entire RSU award is fully vested.