Mountaineer Partners Management, LLC filed a Form 13F-HR with the Securities and Exchange Commission on November 9, 2026, disclosing its equity portfolio as of the close of business on September 30, 2026. The filing lists the firm's principal business address as 950 3rd Avenue, 28th Floor, New York, NY 10022.
The report details the firm's holdings in 28 separate companies. The largest position disclosed in the filing is Constellium SE Class A Shares, for which the firm holds 414,551 shares. The second-largest holding is Century Aluminum Company, with 580,053 shares. Other significant positions include StandardAero Inc. with 436,497 shares, Hudbay Minerals Inc. with 402,429 shares, and Vishay Intertechnology Inc. with 323,172 shares.
The portfolio includes a diverse mix of industrial and technology companies. Notable holdings include Alcoa Corporation, Carpenter Technology Corporation, Sensient Technologies Corporation, and Flex Ltd. Additionally, the filing lists positions in Cameco Corporation, ATI Inc., and StandardAero Inc.
The filing was signed by Mark Lee, the Managing Member of Mountaineer Partners Management, LLC.
