Mammoth Energy Services
TUSK on Nasdaq. Mammoth Energy Services sells equipment rental, drilling, sand and fiber services to energy and utility firms. Market value $137m.
Figures from the annual report for the year ended 31 December 2025.
We can't read total debt from the filing, so debt is left out.
Should I look at this?
Not a fit for our list right now
Why it could be worth it
Nothing stands out yet.
See Energy stocks that passed both tests
This is not advice. Check the numbers below.
For every $100 of what the whole company costs, it produced $-62.14 of spare cash last year. A savings account pays about $4.
The filings do not give us enough to work this out.
Each dollar kept in the business earns -10 cents a year. Above 10 is good.
Quality score: 23 of 100. Price score: 17 of 100. Our list needs 70 on quality and 60 on price.
Five years of cash, in billions
| Revenue | |||||
| Revenue | $229m | $362m | $309m | $46m | $44m |
| Operating margin | |||||
| Operating margin | -53.7% | -4.5% | -5.4% | -263.9% | -129.7% |
| Debt to equity | |||||
| Debt to equity | 0.20 | 0.19 | 0.10 | 0.03 | n/a |
| Shares outstanding | |||||
| Shares outstanding | 0.05bn | 0.05bn | 0.05bn | 0.05bn | 0.05bn |
Health checks
- Free cash flow positive2 of 3 years
- Accounting checksSkipped: company is not yet profitable
- DebtUnknown
- Revenue growth, five yearsShrinking, 32.4% a year
- Buying back its own sharesRoughly flat
Dates
- Next results (estimated)
- n/a
- Last annual report (10-K)
- 6 March 2026
- Next quarterly (estimated, 10-Q)
- 6 November 2026
Who owns it
1 long-term investor we follow owns it, down from 2 last quarter. 94 funds in all.
| Fund | Value | Share of that fund | Change |
|---|---|---|---|
| Boston PartnersBoston Partners team | $224,040 | <0.1% | Cut |
Sold out this quarter
- ValueWorksCharles LemonidesSold out
Largest holders overall
- Wexford Capital LP$39mCut
- Adage Capital Partners GP, L.L.C.$15m
- Vanguard Capital Management$3mAdded
- Peapod Lane Capital$3mAdded
- Dimensional Fund Advisors LP$2m
- Jane Street Group$2mAdded
- Citadel Advisors$1mAdded
- BlackRock$1mCut
- Marshall Wace, LLP$1mNew
- Johns Hopkins University$1mNew
From 13F filings for the quarter ended 30 June 2026.
Big holders and activists
3 investors own more than 5%.
- Wexford Capital LPPassive investorat least 25.1%(filed with 3 related holders)Since 17 June 2026
- Charles E. DavidsonPassive investorat least 13.4%(filed with 1 related holder)Since 17 June 2026
- ValueWorksPassive investorat least 5.0%(filed with 3 related holders)Since 30 June 2025
| Holder | Stake | Since | |
|---|---|---|---|
Wexford Capital LP Passive investor | at least 25.1% (filed with 3 related holders) | 17 June 2026 | |
Charles E. Davidson Passive investor | at least 13.4% (filed with 1 related holder) | 17 June 2026 | |
ValueWorks Passive investor | at least 5.0% (filed with 3 related holders) | 30 June 2025 |
From Schedule 13D and 13G filings: anyone owning more than 5% must file one.
What insiders did
In the last 12 months, 3 insiders bought $11m of shares on the open market.
- Plaumann Mark LawrenceDirectorBought
- Date
- 16 September 2026
- Shares
- 5,000
- Price
- $3.00
- Value
- $15,000
- Wexford GP LLCChief Business Officer, DirectorBought
- Date
- 17 June 2026
- Shares
- 4,019,574
- Price
- $2.60
- Value
- $10m
- Amron Arthur HDirectorBought
- Date
- 12 June 2026
- Shares
- 2,000
- Price
- $3.28
- Value
- $6,560
- Amron Arthur HDirectorBought
- Date
- 11 June 2026
- Shares
- 2,500
- Price
- $3.22
- Value
- $8,050
- Amron Arthur HDirectorBought
- Date
- 28 May 2026
- Shares
- 3,000
- Price
- $3.25
- Value
- $9,750
- Amron Arthur HDirectorBought
- Date
- 26 May 2026
- Shares
- 2,500
- Price
- $3.24
- Value
- $8,100
- Amron Arthur HDirectorBought
- Date
- 11 December 2025
- Shares
- 10,000
- Price
- $1.89
- Value
- $18,900
| Date | Who | Did | Shares | Price | Value |
|---|---|---|---|---|---|
| 16 September 2026 | Plaumann Mark Lawrence Director | Bought | 5,000 | $3.00 | $15,000 |
| 17 June 2026 | Wexford GP LLC Chief Business Officer, Director | Bought | 4,019,574 | $2.60 | $10m |
| 12 June 2026 | Amron Arthur H Director | Bought | 2,000 | $3.28 | $6,560 |
| 11 June 2026 | Amron Arthur H Director | Bought | 2,500 | $3.22 | $8,050 |
| 28 May 2026 | Amron Arthur H Director | Bought | 3,000 | $3.25 | $9,750 |
| 26 May 2026 | Amron Arthur H Director | Bought | 2,500 | $3.24 | $8,100 |
| 11 December 2025 | Amron Arthur H Director | Bought | 10,000 | $1.89 | $18,900 |
From Form 4 filings: insiders must report trades in their own company's shares within two days.
What could go wrong
- Sales have shrunk: 32.4% a year.
Whether the price already reflects the risks is what the deep dive is for.
The deep dive
Everything above is arithmetic on public filings. The deep dive reads the last ten years of annual reports, the proxy statements, and the earnings calls, then argues the case the way Buffett, Klarman, and Hohn would, and checks every claim against the source.
- What the business is worth, as a range, and the margin of safety at today’s price
- Prices to start buying, buy, and buy hard
- The three things that would make this a mistake
- Every number footnoted to the filing it came from
Your first deep dive is free.
Not advice. Numbers on this page come from SEC filings and are updated each night; prices are updated again after the US market closes. The five-year figures are rounded.