Mason Capital Management LLC
In its 13F for Q4 2025 (holdings as of December 31, 2025, filed February 17, 2026), Mason Capital Management LLC reported 9 stock positions worth $561.6 million. Its top holding was Ats (ATS) at 76.3% of the portfolio, followed by Brookdale Senior Living (BKD, 6.9%) and Solstice Adv Materials (SOLS, 5.5%). Compared with Q3 2025, it opened 4 new positions, sold out of 1 and added to 1. The biggest buy was a new position in Solstice Adv Materials (SOLS) and the biggest sale an exit from Kenvue (KVUE).
- Most Recent 13F
- Q2 2026
- Location
- NEW YORK, NY
- CIK
- 0001218735
- Portfolio Value
- $561.6M (Q4 2025)
- SEC Filing
- 0001104659-26-016335 ↗ filed Feb 17, 2026
Holdings Value
Holdings 9 stocks · $561.6M
| ATS Ats Corp. | 76.32% | 15,563,568 | $428.6M | No change |
| BKD Brookdale Senior Living Inc. | 6.89% | 3,585,941 | $38.7M | Add +44.8% |
| SOLS Solstice Adv Materials Inc. | 5.48% | 633,801 | $30.8M | New |
| CCO Clear Channel Outdoor Holdin | 3.87% | 9,828,401 | $21.7M | No change |
| JBS JBS NV-A | 3.35% | 1,306,000 | $18.8M | New |
| BORR Borr Drilling Ltd. | 1.57% | 2,182,136 | $8.8M | New |
| RC Ready Capital Corp. | 1.47% | 3,776,139 | $8.2M | New |
| MLAB Mesa Laboratories Inc. | 0.98% | 70,300 | $5.5M | No change |
| SBNY Signature Bank | 0.07% | 400,000 | $404K | No change |
Portfolio Sells Q3 2025 → Q4 2025
| KVUE Kenvue Inc. | Sold out | 0.00% | −8.57 |
Portfolio Buys Q3 2025 → Q4 2025
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 |