Buy4

Inhibrx Biosciences, Inc.

INBX

Total Value

$849.0K

Net $849.0K bought

Filing Date

Oct 14, 2026

6 transactions

Purchases

$849.0K

6 transactions

Trade Summary

On Oct 14, 2026, Lappe Mark, Chief Executive Officer, Director, purchased $849.0K of Inhibrx Biosciences, Inc. (INBX) across 6 transactions. The filing covers Common Stock and reflects net buying of $849.0K. Reported prices ranged from $84.07 to $85.76. 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 $84.56.

Bought near the 6-month low · about level with today's price.

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

Insider Information

Name: Lappe Mark
Role: Chief Executive Officer, Director
Location: LA JOLLA, CA

Filing Details

Filing Date: Oct 14, 2026
Transaction Date: Oct 14, 2026
Accession Number: 0001366074-26-000006
Form Type: 4
Net Trading Amount: $849.0K

Non-Derivative Transactions

Date	Security	Shares	Price	Type	Value
Oct 14, 2026	Common Stock	2,470	$84.07	Purchase	$207.7K
Oct 14, 2026	Common Stock	2,470	$85.00	Purchase	$209.9K
Oct 14, 2026	Common Stock	100	$85.76	Purchase	$8.6K
Oct 14, 2026	Common Stock	2,449	$84.07	Purchase	$205.9K
Oct 14, 2026	Common Stock	2,451	$85.00	Purchase	$208.3K
Oct 14, 2026	Common Stock	100	$85.76	Purchase	$8.6K

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Footnotes

(F1)The shares were purchased in multiple transactions at prices ranging from $83.61 to $84.59 inclusive. The reported price reflects the weighted-average purchase price. The reporting person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the transactions were effected.
(F2)These securities are directly owned by the Lappe Family Trust. Mark P. Lappe is a trustee of the Lappe Family Trust and, in such capacity, may be deemed to indirectly beneficially own the securities owned by the Lappe Family Trust.
(F3)The shares were purchased in multiple transactions at prices ranging from $84.65 to $85.62 inclusive. The reported price reflects the weighted-average purchase price. The reporting person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the transactions were effected.
(F4)These securities are directly owned by a trust, for the benefit of the reporting person's immediate family. Mark P. Lappe, as an immediate family member of the beneficiaries of the trust, may be deemed to indirectly beneficially own the securities owned by the trust.

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^*

Lappe Mark

(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
X	Officer (give title below)	Other (specify below)
	Chief Executive Officer

3. Date of Earliest Transaction (Month/Day/Year)
10/14/2026

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	10/14/2026		P		2,470	A	$84.0707⁽¹⁾	743,018	I	By the Lappe Family Trust⁽²⁾
Common Stock	10/14/2026		P		2,470	A	$84.9992⁽³⁾	745,488	I	By the Lappe Family Trust⁽²⁾
Common Stock	10/14/2026		P		100	A	$85.76	745,588	I	By the Lappe Family Trust⁽²⁾
Common Stock	10/14/2026		P		2,449	A	$84.0707⁽¹⁾	167,449	I	By Lappe Descendants' Trust⁽⁴⁾
Common Stock	10/14/2026		P		2,451	A	$84.9992⁽³⁾	169,900	I	By Lappe Descendants' Trust⁽⁴⁾
Common Stock	10/14/2026		P		100	A	$85.76	170,000	I	By Lappe Descendants' Trust⁽⁴⁾
Common Stock								54,865	I	The Mark Paul Lappe Roth IRA

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. The shares were purchased in multiple transactions at prices ranging from $83.61 to $84.59 inclusive. The reported price reflects the weighted-average purchase price. The reporting person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the transactions were effected.

2. These securities are directly owned by the Lappe Family Trust. Mark P. Lappe is a trustee of the Lappe Family Trust and, in such capacity, may be deemed to indirectly beneficially own the securities owned by the Lappe Family Trust.

3. The shares were purchased in multiple transactions at prices ranging from $84.65 to $85.62 inclusive. The reported price reflects the weighted-average purchase price. The reporting person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the transactions were effected.

4. These securities are directly owned by a trust, for the benefit of the reporting person's immediate family. Mark P. Lappe, as an immediate family member of the beneficiaries of the trust, may be deemed to indirectly beneficially own the securities owned by the trust.

Remarks:

	/s/ Kelly D. Deck, as attorney-in-fact for Mark P. Lappe	10/14/2026
	** 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 0001366074-26-000006.

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

SEC Form 4

Price at the Time of the Trade