STOCK TITAN

Arcellx (ACLX) CFO exercises options, lifting direct stake to 67,048 shares

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

Rhea-AI Filing Summary

Arcellx, Inc. chief financial officer Michelle Gilson exercised stock options to acquire 38,110 shares of Common Stock. The options were exercised at an exercise price of $8.66 per share on two dates and were granted under Arcellx's 2022 Equity Incentive Plan.

After these exercises, she holds 67,048 Common Stock shares directly. In addition, a family charitable foundation, for which she serves as President and over whose securities she has voting and investment power, holds 5,000 Common Stock shares indirectly. No open-market purchases or sales were reported in this filing.

Positive

  • None.

Negative

  • None.
Insider Gilson Michelle
Role CHIEF FINANCIAL OFFICER
Type Security Shares Price Value
Exercise Stock Option (right to buy) 2,110 $0.00 --
Exercise Common Stock 2,110 $8.66 $18K
Exercise Stock Option (right to buy) 36,000 $0.00 --
Exercise Common Stock 36,000 $8.66 $312K
holding Common Stock -- -- --
Holdings After Transaction: Stock Option (right to buy) — 40,205 shares (Direct); Common Stock — 67,048 shares (Direct); Common Stock — 5,000 shares (Indirect, By Foundation)
Footnotes (1)
  1. Shares held by a a family charitable foundation, of which the Reporting Person serves as the President. The Reporting Person has voting and investment power over all securities owned by the foundation. Shares issued pursuant to the Issuer's 2022 Equity Incentive Plan (the "2022 Plan"). Subject to the Reporting Person continuing to be a Service Provider (as defined in the Issuer's 2022 Equity Incentive Plan) through each applicable vesting date, twenty-five percent (25%) of the shares subject to the Option shall vest on the one (1) year anniversary of the Vesting Commencement Date, and one forty-eighth (1/48th) of the shares subject to the Option shall vest each month thereafter on the same day of the month as the Vesting Commencement Date (and if there is no corresponding day, on the last day of the month), "Vesting Commencement Date" shall mean May 23, 2022.
Options exercised 38,110 shares Total Common Stock acquired via option exercises reported
Exercise price $8.66 per share Strike price for exercised stock options
Direct holdings after transactions 67,048 shares Common Stock directly owned by CFO post-exercise
Indirect foundation holdings 5,000 shares Common Stock held by family charitable foundation
Options exercised on 2026-04-15 36,000 shares Common Stock underlying options exercised on April 15, 2026
Options exercised on 2026-04-16 2,110 shares Common Stock underlying options exercised on April 16, 2026
Option expiration May 23, 2032 Expiration date of the stock options exercised
Stock Option (right to buy) financial
"security_title: Stock Option (right to buy)"
2022 Equity Incentive Plan financial
"Shares issued pursuant to the Issuer's 2022 Equity Incentive Plan"
Vesting Commencement Date financial
"“Vesting Commencement Date” shall mean May 23, 2022"
The vesting commencement date is the starting point when an employee begins earning ownership rights to their promised benefits, such as stock options or retirement contributions. Think of it like the day a savings account is opened—only after this date do the benefits start to grow and become fully available over time. It matters to investors because it marks when the clock begins ticking toward full ownership, affecting the timing and value of these benefits.
Service Provider financial
"subject to the Reporting Person continuing to be a Service Provider"
family charitable foundation financial
"Shares held by a a family charitable foundation"
SEC Form 4
FORM 4UNITED 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*
Gilson Michelle

(Last)(First)(Middle)
C/O ARCELLX, INC.
800 BRIDGE PARKWAY

(Street)
REDWOOD CITY CALIFORNIA 94065

(City)(State)(Zip)

UNITED STATES

(Country)
2. Issuer Name and Ticker or Trading Symbol
Arcellx, Inc. [ ACLX ]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
Director10% Owner
XOfficer (give title below)Other (specify below)
CHIEF FINANCIAL OFFICER
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
04/15/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm 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)
CodeVAmount(A) or (D)Price
Common Stock04/15/2026M36,000A$8.6664,938D
Common Stock04/16/2026M2,110A$8.6667,048D
Common Stock5,000I(1)By Foundation
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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Stock Option (right to buy)$8.6604/15/2026M36,000 (2)05/23/2032Common Stock36,000$042,315D
Stock Option (right to buy)$8.6604/16/2026M2,110 (2)05/23/2032Common Stock2,110$040,205D
Explanation of Responses:
1. Shares held by a a family charitable foundation, of which the Reporting Person serves as the President. The Reporting Person has voting and investment power over all securities owned by the foundation.
2. Shares issued pursuant to the Issuer's 2022 Equity Incentive Plan (the "2022 Plan"). Subject to the Reporting Person continuing to be a Service Provider (as defined in the Issuer's 2022 Equity Incentive Plan) through each applicable vesting date, twenty-five percent (25%) of the shares subject to the Option shall vest on the one (1) year anniversary of the Vesting Commencement Date, and one forty-eighth (1/48th) of the shares subject to the Option shall vest each month thereafter on the same day of the month as the Vesting Commencement Date (and if there is no corresponding day, on the last day of the month), "Vesting Commencement Date" shall mean May 23, 2022.
/s/ Michelle Gilson04/17/2026
** Signature of Reporting PersonDate
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)

FAQ

What insider transaction did Arcellx (ACLX) report for its CFO?

Arcellx reported that CFO Michelle Gilson exercised stock options to acquire 38,110 Common Stock shares. These option exercises are compensation-related events, not open-market purchases or sales, and reflect conversion of options granted under the company’s 2022 Equity Incentive Plan.

At what price did the Arcellx (ACLX) CFO exercise her stock options?

The stock options were exercised at an exercise price of $8.66 per share. This price reflects the predetermined strike price of the options granted earlier under Arcellx’s 2022 Equity Incentive Plan, rather than the market price on the exercise dates.

How many Arcellx (ACLX) shares does the CFO hold after these transactions?

Following the reported option exercises, CFO Michelle Gilson holds 67,048 Arcellx Common Stock shares directly. Additionally, a related family charitable foundation holds 5,000 shares indirectly, over which she has both voting power and investment authority according to the disclosure.

Were any Arcellx (ACLX) shares sold in this Form 4 filing?

No share sales were reported. The filing only shows option exercises classified as derivative conversions, resulting in the acquisition of Common Stock. There are no open-market sales, gifts, or tax-withholding dispositions disclosed in connection with these transactions.

What plan governed the Arcellx (ACLX) CFO’s exercised options?

The exercised options were issued under Arcellx’s 2022 Equity Incentive Plan. Vesting occurs with 25% of the option vesting one year after the May 23, 2022 vesting commencement date, and the remaining shares vesting monthly in equal installments thereafter, subject to continued service.

What is the structure of vesting for the Arcellx (ACLX) CFO’s options?

The option vests 25% on the one-year anniversary of the May 23, 2022 vesting commencement date. The remaining 75% then vests in 1/48th monthly installments on the same calendar day, provided the CFO continues as a service provider to Arcellx throughout each vesting date.