Mountaineer Partners Management, LLC

Position in CSTM — Constellium SE

CIK 1730532 New York, NY

Position in CSTM

as of Mar 31, 2026 · filed May 15, 2026 Compact

Position Value

$16,185,683

+$3,340,087 QoQ

Shares Held

658,490

-3.4% QoQ

Ownership

0.484%

of shares outstanding

% of Portfolio

8.04%

of 13F equity value

Holder Rank

—

not a current holder

Holding Since

Mar 2020

22 quarters on record

Voting authority Sole 86.74771067138452.ToString("F0")% Shared 0.ToString("F0")% None 13.252289328615468.ToString("F0")%

Basic Materials · as of Mar 31, 2026

Mountaineer Partners Management, LLC holds $65,960,923 across 3 Aluminum names. CSTM ranks #2 (24.5% of the industry book) .

#	Ticker	Company	Shares	Value (USD)
1	CENX	Century Aluminum Co	583,997	$34,274,783
2	CSTM	Constellium SE This page	658,490	$16,185,683
3	AA	Alcoa Corp	233,687	$15,500,457

22 filing rows on record

Report Date	Value (USD)	Shares	Change	Type	Discretion	Filed
2026-03-31	$16,185,683	658,490	-3.4%	Shares	Sole	2026-05-15
2025-12-31	$12,845,596	681,464	-18.3%	Shares	Sole	2026-02-13
2025-09-30	$12,406,586	833,776	-1.4%	Shares	Sole	2025-11-14
2025-06-30	$11,247,570	845,682	+56.0%	Shares	Sole	2025-08-14
2025-03-31	$5,469,465	542,068	-38.9%	Shares	Sole	2025-05-15
2024-12-31	$9,111,944	887,239	+61.6%	Shares	Sole	2025-02-14
2024-09-30	$8,928,917	549,134	+9.7%	Shares	Sole	2024-11-15
2024-06-30	$9,439,495	500,769	-9.6%	Shares	Sole	2024-08-14
2024-03-31	$12,249,868	554,042	-9.1%	Shares	Sole	2024-05-15
2023-12-31	$12,171,807	609,810	+6.2%	Shares	Sole	2024-02-14
2023-09-30	$10,445,871	573,949	+0.0%	Shares	Sole	2023-11-14
2023-06-30	$9,868,981	573,778	+15.4%	Shares	Sole	2023-08-14
2023-03-31	$7,599,583	497,355	+47.0%	Shares	Sole	2023-05-15
2022-03-31	$6,089,346	338,297	-43.6%	Shares	Sole	2022-05-16
2021-12-31	$10,742,865	599,825	-1.1%	Shares	Sole	2022-02-14
2021-09-30	$11,393,694	606,693	+2.3%	Shares	Sole	2021-11-15
2021-06-30	$11,241,707	593,230	-28.3%	Shares	Sole	2021-08-16
2021-03-31	$12,163,220	827,430	-5.5%	Shares	Sole	2021-05-14
2020-12-31	$12,243,376	875,152	-11.7%	Shares	Sole	2021-02-12
2020-09-30	$7,783,682	991,552	+143.8%	Shares	Sole	2020-11-13
2020-06-30	$3,123,086	406,652	-54.5%	Shares	Sole	2020-08-13
2020-03-31	$4,660,094	894,452	—	Shares	Sole	2020-05-14
No filing history on record for this holder in this stock.