Buy4

Inhibrx Biosciences, Inc.

INBX

Total Value

$500.0K

Net $500.0K bought

Filing Date

Sep 17, 2026

1 transaction

Purchases

$500.0K

1 transaction

Trade Summary

On Sep 16, 2026, Kayyem Jon Faiz, Director, purchased $500.0K of Inhibrx Biosciences, Inc. (INBX) across 1 transaction. The filing covers Common Stock and reflects net buying of $500.0K. Reported prices ranged from $100.00. Insider transactions are sourced from SEC Form 4 disclosures and should be reviewed alongside company fundamentals and the insider's broader trading history.

Price at the Time of the Trade

INBX daily price with the insider's purchase marked at $100.00.

Bought in the lower half of the 6-month range · the stock trades 2% higher today.

Price data is delayed and provided for context only — not investment advice.

Insider Information

Name: Kayyem Jon Faiz
Role: Director
Location: LA JOLLA, CA

Filing Details

Filing Date: Sep 17, 2026
Transaction Date: Sep 16, 2026
Accession Number: 0001366268-26-000006
Form Type: 4
Net Trading Amount: $500.0K

Non-Derivative Transactions

Date	Security	Shares	Price	Type	Value
Sep 16, 2026	Common Stock	5,000	$100.00	Purchase	$500.0K

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Footnotes

(F1)These securities are directly owned by The Jon F. Kayyem and Paige Gates-Kayyem Family Trust. Jon Faiz Kayyem is the trustee of The Jon Faiz Kayyem and Paige N. Gates Family Trust and he disclaims beneficial ownership of these securities, except to the extent of any indirect pecuniary interest in his distributive shares therein.
(F2)These securities are directly owned by the Jon Faiz Kayyem Revocable Trust, of which Jon Faiz Kayyem is the trustee.
(F3)These securities are directly owned by the Paige-Gates Kayyem Revocable Trust, of which Jon Faiz Kayyem's spouse is the trustee.
(F4)These securities are directly owned by a custodial account managed by the reporting person for the benefit of the reporting person's minor child, Child A. The reporting person disclaims beneficial ownership of these securities, except to the extent of any indirect pecuniary interest in his distributive shares therein.
(F5)These securities are directly owned by a custodial account managed by the reporting person for the benefit of the reporting person's minor child, Child B. The reporting person disclaims beneficial ownership of these securities, except to the extent of any indirect pecuniary interest in his distributive shares therein.

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^*

Kayyem Jon Faiz

(Last)

(First)

(Middle)

C/O INHIBRX BIOSCIENCES, INC.

11025 NORTH TORREY PINES ROAD, SUITE 140

(Street)

LA JOLLA

92037

(City)

(State)

(Zip)

2. Issuer Name and Ticker or Trading Symbol
Inhibrx Biosciences, Inc. [ INBX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	10% Owner
	Officer (give title below)	Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
09/16/2026

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)
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	09/16/2026		P		5,000	A	$100	429,360	I	By The Jon F. Kayyem and Paige Gates-Kayyem Family Trust⁽¹⁾
Common Stock								250,000	I	By Jon Faiz Kayyem Revocable Trust⁽²⁾
Common Stock								250,000	I	By Paige Gates-Kayyem Revocable Trust⁽³⁾
Common Stock								69,843	I	By Child A⁽⁴⁾
Common Stock								69,843	I	By Child B⁽⁵⁾

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)

Explanation of Responses:

1. These securities are directly owned by The Jon F. Kayyem and Paige Gates-Kayyem Family Trust. Jon Faiz Kayyem is the trustee of The Jon Faiz Kayyem and Paige N. Gates Family Trust and he disclaims beneficial ownership of these securities, except to the extent of any indirect pecuniary interest in his distributive shares therein.

2. These securities are directly owned by the Jon Faiz Kayyem Revocable Trust, of which Jon Faiz Kayyem is the trustee.

3. These securities are directly owned by the Paige-Gates Kayyem Revocable Trust, of which Jon Faiz Kayyem's spouse is the trustee.

4. These securities are directly owned by a custodial account managed by the reporting person for the benefit of the reporting person's minor child, Child A. The reporting person disclaims beneficial ownership of these securities, except to the extent of any indirect pecuniary interest in his distributive shares therein.

5. These securities are directly owned by a custodial account managed by the reporting person for the benefit of the reporting person's minor child, Child B. The reporting person disclaims beneficial ownership of these securities, except to the extent of any indirect pecuniary interest in his distributive shares therein.

Remarks:

	/s/ Kelly Deck, as attorney-in-fact to Jon Faiz Kayyem	09/17/2026
	** 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 as rendered by the SEC from accession 0001366268-26-000006.

Inhibrx Biosciences, Inc.

Trade Summary

Price at the Time of the Trade

Company Information

Insider Information

Filing Details

Non-Derivative Transactions

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Footnotes

SEC Form 4

SEC Filing

Price at the Time of the Trade

SEC Form 4