Mark P. Lappe - 14 Oct 2026 Form 4 Insider Report for Inhibrx Biosciences, Inc. (INBX)

Reporting relationship: Chief Executive Officer, Director
Issuer ticker: INBX
Reported as of: 14 Oct 2026
Net transaction value: +$848,977
SEC form: 4
Accepted by SEC: 14 Oct 2026, 18:58:14 UTC
Prior SEC filing: 28 Sep 2026
Source filing: View source filing
Reporting owner signature: /s/ Kelly D. Deck, as attorney-in-fact for Mark P. Lappe

Key filing fact

Mark P. Lappe filed Form 4 for Inhibrx Biosciences, Inc. (INBX) on 14 Oct 2026.

Key facts

This page summarizes Mark P. Lappe's Form 4 filing for Inhibrx Biosciences, Inc. (INBX).
6 reported transactions and 0 derivative rows are listed below.
Accepted by SEC: 14 Oct 2026, 18:58.

Change

Previous filing in this sequence was filed on 28 Sep 2026.
Current net transaction value: +$848,977.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001366074 Primary reporting owner

Lappe Mark

Relationship: Chief Executive Officer, Director
Address: C/O INHIBRX BIOSCIENCES, INC., 11025 NORTH TORREY PINES ROAD, SUITE 140, LA JOLLA
Signature: /s/ Kelly D. Deck, as attorney-in-fact for Mark P. Lappe
Signature date: 14 Oct 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

INBX transaction

Common Stock

Purchase

Transaction value: $207,655
Shares: +2,470
Change %: +0.33%
Price: $84.07
Shares after: 743,018
Date: 14 Oct 2026
Ownership: By the Lappe Family Trust
Footnotes: F1, F2

INBX transaction

Common Stock

Purchase

Transaction value: $209,948
Shares: +2,470
Change %: +0.33%
Price: $85.00
Shares after: 745,488
Date: 14 Oct 2026
Ownership: By the Lappe Family Trust
Footnotes: F2, F3

INBX transaction

Common Stock

Purchase

Transaction value: $8,576
Shares: +100
Change %: +0.01%
Price: $85.76
Shares after: 745,588
Date: 14 Oct 2026
Ownership: By the Lappe Family Trust
Footnotes: F2

INBX transaction

Common Stock

Purchase

Transaction value: $205,889
Shares: +2,449
Change %: +1.5%
Price: $84.07
Shares after: 167,449
Date: 14 Oct 2026
Ownership: By Lappe Descendants' Trust
Footnotes: F1, F4

INBX transaction

Common Stock

Purchase

Transaction value: $208,333
Shares: +2,451
Change %: +1.5%
Price: $85.00
Shares after: 169,900
Date: 14 Oct 2026
Ownership: By Lappe Descendants' Trust
Footnotes: F3, F4

INBX transaction

Common Stock

Purchase

Transaction value: $8,576
Shares: +100
Change %: +0.06%
Price: $85.76
Shares after: 170,000
Date: 14 Oct 2026
Ownership: By Lappe Descendants' Trust
Footnotes: F4

INBX holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 54,865
Date: 14 Oct 2026
Ownership: The Mark Paul Lappe Roth IRA

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 4 footnotes

Footnote 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.

Footnote 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.

Footnote 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.

Footnote 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.