{"schema_version":"secwatch.filing_event.v1","accession":"0001628280-25-029661","form_type":"8-K","ticker":"TUSK","cik":"0001679268","company_name":"MAMMOTH ENERGY SERVICES, INC.","filed_at":"2025-06-05T23:59:59+00:00","discovered_at":"2026-05-14T18:02:49.310419+00:00","generated_at":"2026-05-19T22:09:55.856345+00:00","sec_items":["5.02"],"event_type":"leadership","sentiment":"neutral","materiality_score":0.7,"calibrated_materiality_score":0.7,"confidence":"high","headline":"Mammoth Energy CEO Phil Lancaster resigns; son Bernard named COO; board changes","bullets":["CEO Phil Lancaster resigns effective June 30, 2025; will become non-voting board observer June 11.","Bernard Lancaster, son of Phil, appointed COO and Principal Executive Officer effective July 1, 2025.","Paul Jacobi appointed Chief Business Officer effective July 1; resigns from board committees, loses independent status.","Arthur Smith to retire from board at June 11 annual meeting; Mark Plaumann appointed audit committee chair and director."],"urls":{"canonical":"https://secwatch.observer/filing/0001628280-25-029661","json":"https://secwatch.observer/filing/0001628280-25-029661.json","markdown":"https://secwatch.observer/filing/0001628280-25-029661.md","text":"https://secwatch.observer/filing/0001628280-25-029661.txt","edgar_index":"https://www.sec.gov/Archives/edgar/data/1679268/000162828025029661/0001628280-25-029661-index.htm","edgar_primary_document":"https://www.sec.gov/Archives/edgar/data/1679268/000162828025029661/tusk-20250530.htm"},"model":{"generated_by":"deepseek-v4-flash:cloud@v2","generated_at":"2026-05-19T22:09:55.856345+00:00"},"review":{"review_status":"machine_generated","human_reviewed":false,"corrected":false,"correction_note":null,"correction_timestamp":null,"superseded_by":null,"related_filings":[]},"source_grounded_claims":[{"claim_id":"146cfd0f78","claim":"Paul Jacobi was appointed as Chief Business Officer at MAMMOTH ENERGY SERVICES, INC..","evidence_excerpt":"the Board named Paul Jacobi as the Company's Chief Business Officer effective July 1, 2025.","evidence_source":"SEC 8-K Item 5.02","evidence_url":"https://www.sec.gov/Archives/edgar/data/1679268/000162828025029661/0001628280-25-029661-index.htm","confidence":0.95,"family_label":"Executive change","details":[{"label":"Action","value":"appointed"},{"label":"Role","value":"Chief Business Officer"}],"fact_type":"executive_change"},{"claim_id":"2d2c08b216","claim":"Bernard Lancaster was appointed as Chief Operating Officer and Principal Executive Officer at MAMMOTH ENERGY SERVICES, INC..","evidence_excerpt":"the Board named Bernard Lancaster as Chief Operating Officer and Principal Executive Officer of the Company effective July 1, 2025.","evidence_source":"SEC 8-K Item 5.02","evidence_url":"https://www.sec.gov/Archives/edgar/data/1679268/000162828025029661/0001628280-25-029661-index.htm","confidence":0.95,"family_label":"Executive change","details":[{"label":"Action","value":"appointed"},{"label":"Role","value":"Chief Operating Officer and Principal Executive Officer"}],"fact_type":"executive_change"},{"claim_id":"ce0036e027","claim":"Arthur Smith departed as Director at MAMMOTH ENERGY SERVICES, INC..","evidence_excerpt":"Arthur Smith, who has served as a director of the Company since the Company's initial public offering, will not stand for re-election at the Company's 2025 Annual Meeting of Stockholders on June 11, 2025 (the \"2025 Annual Meeting\"), and will retire as a director, chairman of the audit committee and member of the compensation committee and nominating and corporate governance committee, effective as of the date of the 2025 Annual Meeting.","evidence_source":"SEC 8-K Item 5.02","evidence_url":"https://www.sec.gov/Archives/edgar/data/1679268/000162828025029661/0001628280-25-029661-index.htm","confidence":0.95,"family_label":"Executive change","details":[{"label":"Action","value":"will not stand for re-election, will retire"},{"label":"Role","value":"Director"}],"fact_type":"executive_change"},{"claim_id":"f11c9c282a","claim":"Phil Lancaster resigned as Chief Executive Officer at MAMMOTH ENERGY SERVICES, INC..","evidence_excerpt":"Mr. P. Lancaster has resigned from his CEO with Mammoth effective as of June 30, 2025.","evidence_source":"SEC 8-K Item 5.02","evidence_url":"https://www.sec.gov/Archives/edgar/data/1679268/000162828025029661/0001628280-25-029661-index.htm","confidence":0.95,"family_label":"Executive change","details":[{"label":"Action","value":"resigned"},{"label":"Role","value":"Chief Executive Officer"}],"fact_type":"executive_change"}],"license":"Source filings: public domain (SEC EDGAR). Summaries (headline + bullets): CC-BY-4.0; attribute https://secwatch.observer"}