MGNX's three largest insider shareholders as of August 29, 2026 are Target N V Biotech (TenPercentOwner, 9.93Mn shares), Target N V Biotech (TenPercentOwner, 9.93Mn shares), Scott Koenig (President And Ceo, 867.24K shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Target N V Biotech | TenPercentOwner | 9,929,963 | 0 | 9,929,963 | 85.7% | 04 Oct, 2023 |
| 2 | Scott Koenig | President And Ceo | 867,240 | 0 | 867,240 | 7.5% | 17 Feb, 2026 |
| 3 | James Karrels | Svp And Cfo | 206,037 | 0 | 206,037 | 1.8% | 17 Feb, 2026 |
| 4 | Ezio Bonvini | Sr Vp, Research Cso | 185,799 | 0 | 185,799 | 1.6% | 18 Aug, 2026 |
| 5 | William K Heiden | Director | 114,750 | 0 | 114,750 | 1.0% | 20 May, 2026 |
| 6 | Eric Blasius Risser | President And Ceo | 77,169 | 0 | 77,169 | 0.7% | 17 Feb, 2026 |
| 7 | Edward Hurwitz | Director | 47,824 | 0 | 47,824 | 0.4% | 20 May, 2026 |
| 8 | Thomas Spitznagel | Sr Vp, Technical Ops | 38,543 | 0 | 38,543 | 0.3% | 17 Feb, 2026 |
| 9 | Stephen L. Eck | Chief Medical Officer | 29,377 | 0 | 29,377 | 0.3% | 19 Feb, 2025 |
| 10 | Jay Philip Siegel | Director | 14,750 | 0 | 14,750 | 0.1% | 20 May, 2026 |
| 11 | Meenu Chhabra | Director | 14,750 | 0 | 14,750 | 0.1% | 20 May, 2026 |
| 12 | Margaret Liu | Director | 14,750 | 0 | 14,750 | 0.1% | 20 May, 2026 |
| 13 | Karen Jean Ferrante | Director | 14,750 | 0 | 14,750 | 0.1% | 20 May, 2026 |
| 14 | Beth Ann Smith | Vp, Controller Treasurer | 12,781 | 0 | 12,781 | 0.1% | 17 Feb, 2026 |
| 15 | Scott Thomas Jackson | Director | 11,000 | 0 | 11,000 | 0.1% | 22 May, 2025 |
| 16 | Lynn Cilinski | Vp, Controller And Treasurer | 6,213 | 0 | 6,213 | 0.1% | 20 Feb, 2024 |
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 |
|---|---|---|---|---|---|---|---|---|
| 19 Aug, 2026 | Jeffrey Stuart Peters | Senior Vp, Gc, And Secretary | Disposed S | 31,105 | $4.15 | $129.09K | 0 | Direct |
| 17 Aug, 2026 | Ezio Bonvini | Sr Vp, Research Cso | Acquired M | 40,000 | $2.60 | $104.00K | 185,799 | Direct |
| 17 Aug, 2026 | Ezio Bonvini | Sr Vp, Research Cso | Disposed M | 40,000 | $2.60 | $104.00K | 88,000 | Direct |
| 18 May, 2026 | William K Heiden | Director | Acquired M | 3,750 | — | — | 114,750 | Direct |
| 18 May, 2026 | Jay Philip Siegel | Director | Acquired M | 3,750 | — | — | 14,750 | Direct |
| 18 May, 2026 | Karen Jean Ferrante | Director | Acquired M | 3,750 | — | — | 14,750 | Direct |
| 18 May, 2026 | Margaret Liu | Director | Acquired M | 3,750 | — | — | 14,750 | Direct |
| 18 May, 2026 | Meenu Chhabra | Director | Acquired M | 3,750 | — | — | 14,750 | Direct |
| 18 May, 2026 | Edward Hurwitz | Director | Acquired M | 3,750 | — | — | 47,824 | Direct |
| 19 May, 2026 | Scott Koenig | Director | Acquired A | 3,750 | $0.00 | $0 | 3,750 | Direct |
| 18 May, 2026 | Jay Philip Siegel | Director | Disposed M | 3,750 | $0.00 | $0 | 0 | Direct |
| 18 May, 2026 | William K Heiden | Director | Disposed M | 3,750 | $0.00 | $0 | 0 | Direct |
| 19 May, 2026 | Meenu Chhabra | Director | Acquired A | 22,000 | $0.00 | $0 | 22,000 | Direct |
| 18 May, 2026 | Margaret Liu | Director | Disposed M | 3,750 | $0.00 | $0 | 0 | Direct |
| 18 May, 2026 | Karen Jean Ferrante | Director | Disposed M | 3,750 | $0.00 | $0 | 0 | Direct |
| 18 May, 2026 | Edward Hurwitz | Director | Disposed M | 3,750 | $0.00 | $0 | 0 | Direct |
| 19 May, 2026 | Scott Koenig | Director | Acquired A | 22,000 | $0.00 | $0 | 22,000 | Direct |
| 19 May, 2026 | Meenu Chhabra | Director | Acquired A | 3,750 | $0.00 | $0 | 3,750 | Direct |
| 19 May, 2026 | Edward Hurwitz | Director | Acquired A | 3,750 | $0.00 | $0 | 3,750 | Direct |
| 19 May, 2026 | Margaret Liu | Director | Acquired A | 3,750 | $0.00 | $0 | 3,750 | Direct |