Mammoth Energy Services, Inc.: which funds bought and sold

Institutions that bought and sold Mammoth Energy Services shares in Q2 2026, from the holdings they reported to the SEC on Form 13F for March 31, 2026 and June 30, 2026.

Between March 31, 2026 and June 30, 2026, 61 institutions that filed 13F reports for both quarters added to or opened positions in Mammoth Energy Services, and 46 cut or closed them. Together they sold a net 9.0M shares, −25.6% on what they held at the start of the quarter. Active managers and hedge funds on our list were net buyers of 997K shares (+15.7%); index fund managers were net sellers of 1.8M shares (−45.5%). 29 opened a new position and 23 sold out entirely.

Bought, Q2 2026 61 institutions, 29 of them new holders Sold, Q2 2026 46 institutions, 23 of them sold out

Net change, all compared −9.0M shares (−25.6%)

Net change, active managers +997K shares (+15.7%), 14 bought, 9 sold

Buyers versus sellers

institutions compared, 117

61 bought 10 46 sold

Active managers and hedge funds 14 bought · 9 sold · +997K

Index fund managers 1 bought · 8 sold · −1.8M

Other institutions 46 bought · 29 sold · −8.2M

Biggest buyers

by change in shares held

Biggest buyers
Institution	Change in shares	Shares June 30, 2026	Value
Jane Street Group, LLC	+484K +2117.0%	507K	$1.6M
Marshall Wace, LLP Hedge fund	+396K New position	396K	$1.3M
Johns Hopkins University	+387K New position	387K	$1.3M
Arrowstreet Capital, Limited Partnership Hedge fund	+290K New position	290K	$942,812
Russell Investments Group, Ltd.	+262K +384.8%	330K	$1.1M
Vanguard Capital Management LLC Index funds	+240K +29.4%	1.1M	$3.4M
Peapod Lane Capital LLC	+208K +34.7%	808K	$2.6M
Round Rock Advisors LLC	+153K New position	153K	$496,733
Millennium Management LLC Hedge fund	+124K New position	124K	$403,604
Citadel Advisors LLC Hedge fund	+121K +36.5%	452K	$1.5M
Gsa Capital Partners LLP	+116K +831.4%	130K	$421,000
AQR Capital Management LLC Hedge fund	+111K +166.5%	178K	$577,928
Marquette Asset Management, LLC	+110K New position	110K	$356,935
Fny Investment Advisers, LLC	+76K New position	76K	$248,000
BNP Paribas Financial Markets	+76K +455.1%	93K	$302,133
Point72 Asset Management, L.P. Hedge fund	+72K New position	72K	$234,296
Bank Of America Corp	+71K +279.2%	97K	$315,400
Aster Capital Management (Difc) Ltd	+68K New position	68K	$219,603
Renaissance Technologies LLC Hedge fund	+60K +26.0%	292K	$949,910
Qube Research & Technologies Ltd Hedge fund	+59K New position	59K	$191,292

Biggest buyers, active managers and hedge funds
Institution	Change in shares	Shares June 30, 2026	Value
Marshall Wace, LLP Hedge fund	+396K New position	396K	$1.3M
Arrowstreet Capital, Limited Partnership Hedge fund	+290K New position	290K	$942,812
Millennium Management LLC Hedge fund	+124K New position	124K	$403,604
Citadel Advisors LLC Hedge fund	+121K +36.5%	452K	$1.5M
AQR Capital Management LLC Hedge fund	+111K +166.5%	178K	$577,928
Point72 Asset Management, L.P. Hedge fund	+72K New position	72K	$234,296
Renaissance Technologies LLC Hedge fund	+60K +26.0%	292K	$949,910
Qube Research & Technologies Ltd Hedge fund	+59K New position	59K	$191,292
Two Sigma Investments, LP Hedge fund	+59K New position	59K	$190,249
Walleye Capital LLC Hedge fund	+49K New position	49K	$159,708

Biggest sellers

by change in shares held

Biggest sellers
Institution	Change in shares	Shares June 30, 2026	Value
Wexford Capital LP	−10.0M −45.3%	12.1M	$39.2M
Blackrock, Inc. Index funds	−1.0M −72.0%	408K	$1.3M
State Street Corp Index funds	−320K −75.9%	102K	$331,058
Geode Capital Management, LLC Index funds	−305K −49.9%	306K	$995,730
Goldman Sachs Group Inc	−169K −75.4%	55K	$178,516
Los Angeles Capital Management LLC Active manager	−163K Sold out	0	—
Vanguard Portfolio Management LLC Index funds	−140K Sold out	0	—
Northern Trust Corp Index funds	−130K −69.4%	57K	$185,835
Boston Partners Active manager	−85K −55.3%	69K	$224,040
Acadian Asset Management LLC Active manager	−82K −40.2%	122K	$396,000
Osaic Holdings, Inc.	−72K −99.8%	150	$487
Bank Of New York Mellon Corp	−71K −53.2%	62K	$201,523
Squarepoint Ops LLC Hedge fund	−52K Sold out	0	—
Charles Schwab Investment Management Inc Index funds	−48K −81.8%	11K	$34,902
Nuveen, LLC	−37K Sold out	0	—
Occudo Quantitative Strategies LP	−29K Sold out	0	—
Levin Capital Strategies, L.P. Active manager	−25K Sold out	0	—
Verdad Advisers, LP	−23K Sold out	0	—
Wellington Management Group LLP Active manager	−21K −30.6%	47K	$154,330
Morgan Stanley	−19K −12.5%	134K	$434,070

Biggest sellers, active managers and hedge funds
Institution	Change in shares	Shares June 30, 2026	Value
Los Angeles Capital Management LLC Active manager	−163K Sold out	0	—
Boston Partners Active manager	−85K −55.3%	69K	$224,040
Acadian Asset Management LLC Active manager	−82K −40.2%	122K	$396,000
Squarepoint Ops LLC Hedge fund	−52K Sold out	0	—
Levin Capital Strategies, L.P. Active manager	−25K Sold out	0	—
Wellington Management Group LLP Active manager	−21K −30.6%	47K	$154,330
Price T Rowe Associates Inc Active manager	−13K Sold out	0	—
Alliancebernstein L.P. Active manager	−11K Sold out	0	—
Schonfeld Strategic Advisors LLC Hedge fund	−1,461 −8.0%	17K	$54,807

New positions

largest by value

Institution	Shares	Value June 30, 2026
Marshall Wace, LLPHedge fund	396K	$1.3M
Johns Hopkins University	387K	$1.3M
Arrowstreet Capital, Limited PartnershipHedge fund	290K	$942,812
Round Rock Advisors LLC	153K	$496,733
Millennium Management LLCHedge fund	124K	$403,604
Marquette Asset Management, LLC	110K	$356,935
Fny Investment Advisers, LLC	76K	$248,000
Point72 Asset Management, L.P.Hedge fund	72K	$234,296
Aster Capital Management (Difc) Ltd	68K	$219,603
Qube Research & Technologies LtdHedge fund	59K	$191,292

Sold out

largest by value

Institution	Shares	Value March 31, 2026
Los Angeles Capital Management LLCActive manager	163K	$399,984
Vanguard Portfolio Management LLCIndex funds	140K	$343,355
Squarepoint Ops LLCHedge fund	52K	$126,469
Nuveen, LLC	37K	$90,265
Occudo Quantitative Strategies LP	29K	$83,901
Levin Capital Strategies, L.P.Active manager	25K	$61,250
Verdad Advisers, LP	23K	$55,686
Sanctuary Advisors, LLC	17K	$40,856
Sei Investments Co	14K	$33,269
Price T Rowe Associates IncActive manager	13K	$33,000

Who holds the shares

13F holdings at June 30, 2026

Institutions reporting: 94
Ten largest holders: 81.9%
Index fund managers: 8.1%
Active managers and hedge funds: 28.3%

Buying and selling by type of institution, March 31, 2026 to June 30, 2026
Type	Bought	Sold	New	Sold out	Net change in shares	Net %
Active managers and hedge funds	14	9	9	5	+997K	+15.7%
Index fund managers	1	8	0	1	−1.8M	−45.5%
Other institutions	46	29	20	17	−8.2M	−33.1%

Active managers and hedge funds: a list we maintain of about 400 well-known stock-picking firms and hedge funds, matched by SEC registration number (CIK) and checked against the filer names each quarter. Index fund managers: the large index houses, such as BlackRock, Vanguard, State Street, Geode and Northern Trust. Every other filer (banks, brokers, wealth managers, pension funds, insurers and firms not on the list) counts as another institution. A firm that files under several SEC registrations appears once for each.

What these filings can and cannot tell you

Form 13F lists the long positions in US-listed shares held by investment managers with more than $100 million in such holdings. Managers file it up to 45 days after each quarter ends, so this page shows what funds held at the end of each quarter, not what they are doing now: a position may have changed since. Short positions, most derivatives and smaller managers are not included, and a cut can mean a fund lost clients or rebalanced rather than a view on Mammoth Energy Services.

Only managers that filed a holdings report for both quarters are compared (117 here). 1 other holder is left out: first-time or late filers, firms that changed their SEC registration, and filings that withheld positions under confidential treatment, any of which would otherwise look like a new position or a sale. Figures are as reported by each manager in the SEC's quarterly 13F data sets; option positions are excluded.

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