Mason Capital Management portfolio
Single-position portfolioPortfolio as of Jun 30, 2026 (Q2 2026) · filed with the SEC on Aug 14, 2026 · data updated on Nov 5, 2026 · Q2 2026 13F (filing) ↗ · all its 13F filings ↗
A 13F shows the portfolio at quarter-end and is filed up to 45 days later: these are not real-time positions and they may have changed.
Mason Capital Management reported a $607M portfolio of 9 positions to the SEC as of the end of Q2 2026. Its largest positions are ATS, BKD, NVRI. During the quarter it opened Groupon.
Sections with a free account
What it reported after the quarter end (Q2 2026)
The 13F shows the portfolio as of Jun 30, 2026. Since then Mason Capital Management has filed these own trades with the SEC (Form 4, when it owns more than 10% of a company or holds a role in it) and stakes above 5% (13D and 13G). It is not everything it did: only what it must report before the next 13F.
What changed this quarter
5 positions with a change (2 new, 2 added to, 1 trimmed). 4 are listed here: those of 0.5 points of the portfolio or more (up to 12).
- Enviri−61%fewer sharesReduced14.4% → 6.4%
- Groupon+2.6 ppof portfolioNew— → 2.6%
- Brookdale Senior Living+15%more sharesIncreased5.0% → 6.8%
- JELD-WEN Holding+300%more sharesIncreased0.2% → 0.8%
The figure on the right: for positions added to or trimmed, the change in the number of shares (%); for new and sold ones, the points of the portfolio moved (pp). Below, the portfolio weight before → after. Traded weight: what it bought or sold, excluding price effects.
Top holdings
- ATSATS77.8%
- Brookdale Senior LivingBKD6.8%
- EnviriNVRI6.4%
- Clear Channel Outdoor HoldingsCCO3.9%
- GrouponGRPN2.6%
- Ready CapitalRC1.2%
- JELD-WEN HoldingJELD0.8%
- ContextLogic HoldingsLOGC0.4%
- Signature BankSBNYunder 0.1%
“Since”: first quarter of the current run, unbroken until today. In the details, prices are the quarter-end prices of the quarters in which it added shares, per the 13F. The manager may have bought at any price within each quarter; the SEC only publishes the value at quarter end.
Portfolio by sector
- ● Industrials 88%
- ● Health Care 7%
- ● Consumer Discretionary 3%
- ● Real Estate 1%
- ● Materials 1%
How its portfolio changed (8 quarters)
Q2 2026: 9
Q2 2026: 100%
Q2 2026: 7.1%
Traded turnover: the weight it bought plus the weight it sold in the quarter, divided by two, excluding price moves. The plain “turnover” in the header does include that effect. With a free account: the full history and sectors over time.
Stakes above 5% (13D/13G)
Companies where this filer reported holding 5% or more of the shares. It is the figure from its latest filing on each one; history since December 2024.
How we classify it
Single-position portfolio, per its Form ADV of Mar 31, 2026 (high confidence).
The data, as reported: MASON CAPITAL MANAGEMENT LLC (CRD 158797): 7.B private funds: 2 hedge, 1 pe (gross assets $2.8 bn); 5.D assets by client type: pooled vehicles 100% (of $2.2 bn)
The type comes from a rule applied to that data. If it looks wrong, tell us.
Not counted as a concentrated manager: a single position is more than 70% of the portfolio. Its portfolio is shown all the same, but it is left out of manager counts, the consensus and the ranking. How this is decided
Managers of a similar size
A 13F portfolio value between a third and three times this one, whatever the type of filer. It is not a comparison of what they hold.
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