Mammoth Energy Services's three largest insider shareholders as of September 29, 2026 are Capital Lp Wexford (Chief Business Officer, 12.07Mn shares), Charles E Davidson (TenPercentOwner, 6.47Mn shares), Arty Straehla (Chief Executive Officer, 1.01Mn shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Capital Lp Wexford | Chief Business Officer | 1,451,034 | 10,620,789 | 12,071,823 | 58.1% | 22 Jun, 2026 |
| 2 | Charles E Davidson | TenPercentOwner | 2,403,831 | 4,066,610 | 6,470,441 | 31.2% | 22 Jun, 2026 |
| 3 | Arty Straehla | Chief Executive Officer | 1,012,107 | 0 | 1,012,107 | 4.9% | 19 Dec, 2023 |
| 4 | Mark E. Layton | Cfo And Secretary | 418,985 | 0 | 418,985 | 2.0% | 07 Mar, 2023 |
| 5 | James D Palm | Director | 240,144 | 0 | 240,144 | 1.2% | 14 Jun, 2024 |
| 6 | Phillip Lancaster | Director | 159,445 | 0 | 159,445 | 0.8% | 01 Jul, 2026 |
| 7 | Arthur L Smith | Director | 130,034 | 0 | 130,034 | 0.6% | 27 May, 2025 |
| 8 | Corey J. Booker | Director | 125,488 | 0 | 125,488 | 0.6% | 26 Nov, 2024 |
| 9 | Arthur H Amron | Director | 86,256 | 10,329 | 96,585 | 0.5% | 22 Jun, 2026 |
| 10 | Paul M. Jacobi | Chief Business Officer | 31,067 | 0 | 31,067 | 0.1% | 22 Jun, 2026 |
| 11 | Mark Lawrence Plaumann | Director | 5,000 | 0 | 5,000 | 0.0% | 17 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 |
|---|---|---|---|---|---|---|---|---|
| 16 Sep, 2026 | Mark Lawrence Plaumann | Director | Acquired P | 5,000 | $3.00 | $15.00K | 5,000 | Direct |
| 26 Jun, 2026 | Phillip Lancaster | Director | Acquired J | 68,152 | $0.00 | $0 | 159,445 | Direct |
| 17 Jun, 2026 | Arthur H Amron | Director | Acquired J | 19,121 | $0.00 | $0 | 86,256 | Direct |
| 17 Jun, 2026 | Capital Lp Wexford | Chief Business Officer | Acquired J | 1,072,896 | $0.00 | $0 | 1,451,034 | Direct |
| 17 Jun, 2026 | Charles E Davidson | TenPercentOwner | Acquired J | 2,403,831 | $0.00 | $0 | 2,403,831 | Direct |
| 17 Jun, 2026 | Paul M. Jacobi | Chief Business Officer | Acquired J | 3,211 | $0.00 | $0 | 31,067 | Direct |
| 17 Jun, 2026 | Arthur H Amron | Director | Acquired J | 10,329 | $0.00 | $0 | 10,329 | Indirect |
| 17 Jun, 2026 | Capital Lp Wexford | Chief Business Officer | Acquired J | 6,354,667 | $0.00 | $0 | 6,601,215 | Indirect |
| 17 Jun, 2026 | Charles E Davidson | TenPercentOwner | Acquired J | 4,066,610 | $0.00 | $0 | 4,066,610 | Indirect |
| 17 Jun, 2026 | Capital Lp Wexford | Chief Business Officer | Acquired P | 4,019,574 | $2.60 | $10.47Mn | 10,620,789 | Indirect |
| 11 Jun, 2026 | Arthur H Amron | Director | Acquired P | 2,500 | $3.22 | $8.05K | 65,135 | Direct |
| 12 Jun, 2026 | Arthur H Amron | Director | Acquired P | 2,000 | $3.28 | $6.56K | 67,135 | Direct |
| 26 May, 2026 | Arthur H Amron | Director | Acquired P | 2,500 | $3.24 | $8.10K | 59,635 | Direct |
| 28 May, 2026 | Arthur H Amron | Director | Acquired P | 3,000 | $3.25 | $9.75K | 62,635 | Direct |
| 11 Dec, 2025 | Arthur H Amron | Director | Acquired P | 10,000 | $1.89 | $18.90K | 57,135 | Direct |
| 22 May, 2025 | Arthur L Smith | Director | Disposed S | 20,000 | $2.51 | $50.20K | 130,034 | Direct |
| 19 May, 2025 | Arthur L Smith | Director | Disposed S | 15,000 | $2.49 | $37.35K | 200,034 | Direct |
| 20 May, 2025 | Arthur L Smith | Director | Disposed S | 50,000 | $2.51 | $125.50K | 150,034 | Direct |
| 12 Dec, 2024 | Arthur H Amron | Director | Acquired P | 1,000 | $2.97 | $2.97K | 47,135 | Direct |
| 22 Nov, 2024 | Corey J. Booker | Director | Disposed S | 10,000 | $3.43 | $34.30K | 140,488 | Direct |