Mountaineer Partners Management, LLC 13F Holdings (21 Positions, Q2 2026)

Mountaineer Partners Management, LLC's disclosed holdings carry a Herfindahl concentration index of 0.109 — mathematically equivalent to about 9 equally-sized positions, well below its 21 actual disclosed holdings. That gap points to a strategy built around a small core of high-conviction bets rather than broad diversification.

Position sizes are fairly uniform across the portfolio (a coefficient of variation of 0.47), suggesting a disciplined, rules-based approach to how much capital goes into each idea.

Recent activity leans toward initiating meaningfully larger new positions than it adds to existing ones (a 3.6 percentage-point tilt) — a pattern consistent with a more contrarian, new-idea-driven approach.

Sector classification currently covers about 69% of this portfolio's disclosed value; the remainder includes holdings (e.g. unmapped tickers, options, or other security types) not yet covered by our sector mapping.