Mason Capital Management LLC
In its 13F for Q1 2026 (holdings as of March 31, 2026, filed May 15, 2026), Mason Capital Management LLC reported 7 stock positions worth $612.9 million. Its top holding was Ats (ATS) at 75.5% of the portfolio, followed by Enviri (NVRI, 14.4%) and Brookdale Senior Living (BKD, 5.0%). Compared with Q4 2025, it opened 2 new positions, sold out of 4, added to 2 and reduced 1. The biggest buy was a new position in Enviri (NVRI) and the biggest sale an exit from Solstice Adv Materials (SOLS).
- Most Recent 13F
- Q2 2026
- Location
- NEW YORK, NY
- CIK
- 0001218735
- Portfolio Value
- $612.9M (Q1 2026)
- SEC Filing
- 0001104659-26-062410 ↗ filed May 15, 2026
Holdings Value
Holdings 7 stocks · $612.9M
| ATS Ats Corp. | 75.48% | 16,404,170 | $462.6M | Add +5.4% |
| NVRI Enviri Corp. | 14.39% | 4,494,536 | $88.2M | New |
| BKD Brookdale Senior Living Inc. | 4.99% | 2,233,741 | $30.6M | Reduce -37.7% |
| CCO Clear Channel Outdoor Holdin | 3.80% | 9,828,401 | $23.3M | No change |
| RC Ready Capital Corp. | 1.14% | 4,319,933 | $7.0M | Add +14.4% |
| JELD Jeld-Wen Holding Inc. | 0.16% | 776,885 | $963K | New |
| SBNY Signature Bank | 0.04% | 400,000 | $260K | No change |
Portfolio Sells Q4 2025 → Q1 2026
Portfolio Buys Q4 2025 → Q1 2026
All Filings
| Quarter | Positions | 13F Reported Value | Top Holdings |
|---|---|---|---|
| Q2 2026 | 9 | $607.0M | ATS, BKD, NVRI, CCO, GRPN |
| Q1 2026 | 7 | $612.9M | ATS, NVRI, BKD, CCO, RC |
| Q4 2025 | 9 | $561.6M | ATS, BKD, SOLS, CCO, JBS |
| Q3 2025 | 6 | $491.4M | ATS, KVUE, BKD, CCO, MLAB |
| Q2 2025 | 4 | $511.5M | ATS, CCO, CCIR, SBNY |
| Q1 2025 | 5 | $427.2M | ATS, PARAA, CCO, CCIR, SBNY |
| Q4 2024 | 4 | $470.5M | ATS, CCO, RC, SBNY |
| Q3 2024 | 6 | $502.6M | ATS, MDRX, BARNES GROUP INC, CCO, RC |
| Q2 2024 | 6 | $538.2M | ATS, BARNES GROUP INC, CCO, MDRX, IIIV |
| Q1 2024 | 6 | $727.8M | ATS, BARNES GROUP INC, SDRL, CCO, MDRX |