As of September 29, 2026, the three largest insider holders of MPLX are Michael J Hennigan (Executive Chairman, 359.14K shares), Frank M Semple (Vice Chairman, 333.34K shares), Maryann T. Mannen (Chairman, President Ceo, 165.46K shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Michael J Hennigan | Executive Chairman | 359,137 | 0 | 359,137 | 23.3% | 16 Dec, 2025 |
| 2 | Maryann T. Mannen | Chairman, President Ceo | 165,459 | 0 | 165,459 | 10.7% | 03 Mar, 2026 |
| 3 | Dan D Sandman | Director | 127,542 | 0 | 127,542 | 8.3% | 05 Apr, 2023 |
| 4 | John P Surma | Director | 95,448 | 0 | 95,448 | 6.2% | 18 Aug, 2026 |
| 5 | Gregory Scott Floerke | Exec. Vp And Coo | 95,337 | 0 | 95,337 | 6.2% | 03 Mar, 2026 |
| 6 | Christopher A Helms | Director | 86,208 | 0 | 86,208 | 5.6% | 18 Aug, 2026 |
| 7 | Donald C. Templin | President | 81,538 | 0 | 81,538 | 5.3% | 23 Nov, 2021 |
| 8 | Garry L. Peiffer | President | 69,313 | 0 | 69,313 | 4.5% | 18 Aug, 2026 |
| 9 | Suzanne Gagle | General Counsel | 67,205 | 0 | 67,205 | 4.4% | 05 Dec, 2023 |
| 10 | Frank M Semple | Vice Chairman | 63,476 | 0 | 63,476 | 4.1% | 18 Aug, 2026 |
| 11 | J Michael Stice | Director | 58,413 | 0 | 58,413 | 3.8% | 18 Aug, 2026 |
| 12 | John J Quaid | Exec Vp And Cfo | 52,393 | 0 | 52,393 | 3.4% | 04 Mar, 2025 |
| 13 | Molly R Benson | Chief Legal Ofc Corp Sec | 46,114 | 0 | 46,114 | 3.0% | 03 Mar, 2026 |
| 14 | Pamela K.M. Beall | Exec Vp And Cfo | 43,247 | 0 | 43,247 | 2.8% | 13 Dec, 2021 |
| 15 | Timothy J Aydt | Exec. Vp And Chief Comm Ofc. | 34,371 | 0 | 34,371 | 2.2% | 03 Mar, 2022 |
| 16 | Shawn M Lyon | Senior Vp, Log. Storage | 28,289 | 0 | 28,289 | 1.8% | 03 Mar, 2026 |
| 17 | Carl Kristopher Hagedorn | Exec Vp Chief Fin Ofc | 20,409 | 0 | 20,409 | 1.3% | 03 Mar, 2026 |
| 18 | Thomas Kaczynski | Senior Vp, Finance Treasurer | 18,091 | 0 | 18,091 | 1.2% | 06 Dec, 2022 |
| 19 | Christine S Breves | Director | 15,038 | 0 | 15,038 | 1.0% | 18 Aug, 2026 |
| 20 | Maria A Khoury | Director | 8,451 | 0 | 8,451 | 0.5% | 03 Mar, 2026 |
| 21 | Ray N Jr Walker | Director | 4,609 | 0 | 4,609 | 0.3% | 18 Aug, 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 |
|---|---|---|---|---|---|---|---|---|
| 14 Aug, 2026 | Christine S Breves | Director | Acquired A | 219 | $0.00 | $0 | 15,038 | Direct |
| 14 Aug, 2026 | Frank M Semple | Director | Acquired A | 1,073 | $0.00 | $0 | 63,476 | Direct |
| 14 Aug, 2026 | J Michael Stice | Director | Acquired A | 983 | $0.00 | $0 | 58,413 | Direct |
| 14 Aug, 2026 | Ray N Jr Walker | Director | Acquired A | 82 | $0.00 | $0 | 4,609 | Direct |
| 14 Aug, 2026 | Garry L. Peiffer | Director | Acquired A | 1,232 | $0.00 | $0 | 69,313 | Direct |
| 14 Aug, 2026 | Christopher A Helms | Director | Acquired A | 1,337 | $0.00 | $0 | 86,208 | Direct |
| 14 Aug, 2026 | John P Surma | Director | Acquired A | 1,563 | $0.00 | $0 | 95,448 | Direct |
| 15 May, 2026 | John P Surma | Director | Acquired A | 1,656 | $0.00 | $0 | 93,426 | Direct |
| 15 May, 2026 | Ray N Jr Walker | Director | Acquired A | 78 | $0.00 | $0 | 4,069 | Direct |
| 15 May, 2026 | Christopher A Helms | Director | Acquired A | 1,415 | $0.00 | $0 | 84,413 | Direct |
| 15 May, 2026 | Garry L. Peiffer | Director | Acquired A | 1,304 | $0.00 | $0 | 67,623 | Direct |
| 15 May, 2026 | J Michael Stice | Director | Acquired A | 1,098 | $0.00 | $0 | 56,973 | Direct |
| 15 May, 2026 | Frank M Semple | Director | Acquired A | 1,194 | $0.00 | $0 | 61,946 | Direct |
| 15 May, 2026 | Christine S Breves | Director | Acquired A | 277 | $0.00 | $0 | 14,361 | Direct |
| 30 Apr, 2026 | Christine S Breves | Director | Acquired A | 2,247 | $0.00 | $0 | 14,084 | Direct |
| 30 Apr, 2026 | Ray N Jr Walker | Director | Acquired A | 2,247 | $0.00 | $0 | 3,991 | Direct |
| 30 Apr, 2026 | Garry L. Peiffer | Director | Acquired A | 2,247 | $0.00 | $0 | 66,319 | Direct |
| 30 Apr, 2026 | J Michael Stice | Director | Acquired A | 2,580 | $0.00 | $0 | 55,875 | Direct |
| 30 Apr, 2026 | Frank M Semple | Director | Acquired A | 2,580 | $0.00 | $0 | 60,752 | Direct |
| 30 Apr, 2026 | Christopher A Helms | Director | Acquired A | 2,247 | $0.00 | $0 | 82,998 | Direct |