Inhibrx Biosciences's top three insider shareholders as of September 29, 2026 are Inc. Inhibrx, (TenPercentOwner, 1.16Mn shares), Mark Lappe (Chief Executive Officer, 740.55K shares), Jon Faiz Kayyem (Director, 639.69K shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Inc. Inhibrx, | TenPercentOwner | 1,157,926 | 0 | 1,157,926 | 36.6% | 31 May, 2024 |
| 2 | Mark Lappe | Chief Executive Officer | 0 | 740,548 | 740,548 | 23.4% | 28 Sep, 2026 |
| 3 | Brendan P. Eckelman | Chief Scientific Officer | 0 | 473,888 | 473,888 | 15.0% | 30 May, 2024 |
| 4 | Jon Faiz Kayyem | Director | 0 | 434,360 | 434,360 | 13.7% | 23 Sep, 2026 |
| 5 | Douglas Forsyth | Director | 0 | 227,064 | 227,064 | 7.2% | 08 Sep, 2026 |
| 6 | Global Investors Lp Viking | TenPercentOwner | 0 | 102,864 | 102,864 | 3.3% | 09 Oct, 2025 |
| 7 | Kristiina Md Vuori | Director | 20,443 | 0 | 20,443 | 0.6% | 07 Oct, 2024 |
| 8 | Kimberly Manhard | Director | 0 | 7,500 | 7,500 | 0.2% | 15 Sep, 2026 |
Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.
| Date | Insider | Position | Transaction | Shares | Price | Value | Shares Held After | Ownership |
|---|---|---|---|---|---|---|---|---|
| 25 Sep, 2026 | Mark Lappe | Chief Executive Officer | Acquired P | 3,324 | $98.87 | $328.63K | 733,872 | Indirect |
| 25 Sep, 2026 | Mark Lappe | Chief Executive Officer | Acquired P | 2,176 | $99.60 | $216.73K | 736,048 | Indirect |
| 28 Sep, 2026 | Mark Lappe | Chief Executive Officer | Acquired P | 1,500 | $98.88 | $148.32K | 737,548 | Indirect |
| 28 Sep, 2026 | Mark Lappe | Chief Executive Officer | Acquired P | 3,000 | $101.70 | $305.11K | 740,548 | Indirect |
| 23 Sep, 2026 | Jon Faiz Kayyem | Director | Acquired P | 5,000 | $100.00 | $500.00K | 434,360 | Indirect |
| 16 Sep, 2026 | Jon Faiz Kayyem | Director | Acquired P | 5,000 | $100.00 | $500.00K | 429,360 | Indirect |
| 08 Sep, 2026 | Kimberly Manhard | Director | Disposed S | 500 | $115.14 | $57.57K | 9,500 | Indirect |
| 09 Sep, 2026 | Kimberly Manhard | Director | Disposed S | 500 | $115.80 | $57.90K | 9,000 | Indirect |
| 08 Sep, 2026 | Jon Faiz Kayyem | Director | Acquired P | 5,000 | $113.52 | $567.58K | 424,360 | Indirect |
| 08 Sep, 2026 | Mark Lappe | Chief Executive Officer | Acquired P | 5,895 | $99.29 | $585.34K | 711,443 | Indirect |
| 08 Sep, 2026 | Douglas Forsyth | Director | Acquired P | 2,500 | $114.65 | $286.62K | 227,064 | Indirect |
| 08 Sep, 2026 | Mark Lappe | Chief Executive Officer | Acquired P | 6,605 | $100.64 | $664.72K | 718,048 | Indirect |
| 08 Sep, 2026 | Mark Lappe | Chief Executive Officer | Acquired P | 1,100 | $107.12 | $117.84K | 719,148 | Indirect |
| 08 Sep, 2026 | Mark Lappe | Chief Executive Officer | Acquired P | 500 | $108.24 | $54.12K | 719,648 | Indirect |
| 08 Sep, 2026 | Mark Lappe | Chief Executive Officer | Acquired P | 1,219 | $111.88 | $136.38K | 720,867 | Indirect |
| 08 Sep, 2026 | Mark Lappe | Chief Executive Officer | Acquired P | 9,681 | $112.28 | $1.09Mn | 730,548 | Indirect |
| 03 Jun, 2026 | Jon Faiz Kayyem | Director | Acquired A | 15,000 | $0.00 | $0 | 15,000 | Direct |
| 03 Jun, 2026 | Douglas Forsyth | Director | Acquired A | 15,000 | $0.00 | $0 | 15,000 | Direct |
| 03 Jun, 2026 | Kimberly Manhard | Director | Acquired A | 15,000 | $0.00 | $0 | 15,000 | Direct |
| 03 Jun, 2026 | Kristiina Md Vuori | Director | Acquired A | 15,000 | $0.00 | $0 | 15,000 | Direct |