Mason Capital Management LLC 13F holdings
Mason Capital Management LLC reported 9 positions with a total reported value of $607.0M as of 2026-06-30, in its 13F for Q2 2026, filed 2026-08-14. Top holdings by reported value: ATS ATS CORPORATION (77.8%), BKD BROOKDALE SENIOR LIVING INC (6.8%), NVRI ENVIRI CORP (6.4%), CCO CLEAR CHANNEL OUTDOOR HLDGS (3.9%), GRPN GROUPON INC (2.6%). Against 2026-03-31 it opened 2 new positions and exited 0. Next 13F due by 2026-11-14, the legal deadline 45 days after the quarter ending 2026-09-30.
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Top holdings
9 largest of 9 positions · reported value as of 2026-06-30
| Holding | Shares | Reported value | % of portfolio |
|---|---|---|---|
| ATS ATS CORPORATION | 16,404,170 | $472.1M | 77.8% |
| BKD BROOKDALE SENIOR LIVING INC | 2,575,826 | $41.4M | 6.8% |
| NVRI ENVIRI CORP | 1,770,959 | $38.9M | 6.4% |
| CCO CLEAR CHANNEL OUTDOOR HLDGS | 9,828,401 | $23.8M | 3.9% |
| GRPN GROUPON INC | 657,144 | $15.8M | 2.6% |
| RC READY CAPITAL CORP | 4,319,933 | $7.6M | 1.2% |
| JELD JELD-WEN HOLDING INC | 3,109,621 | $4.7M | 0.8% |
| LOGC CONTEXTLOGIC HOLDINGS INC | 291,341 | $2.6M | 0.4% |
| SIGNATURE BANK | 400,000 | $180.0K | <0.1% |
SEC FORM 13F · Q2 2026 · VALUES AS REPORTED, NOT PRICES
New positions this quarter
Held at 2026-06-30, not at 2026-03-31 · 2 in all · reported value as of 2026-06-30
Sold out
Held at 2026-03-31, gone by 2026-06-30 · 0 in all · reported value as of 2026-03-31
No positions were sold out.
Biggest increases and decreases
Positions held at both quarter ends, by change in shares · reported value as of 2026-06-30
Increases
| Holding | Shares 2026-03-31 | Shares 2026-06-30 | Change | Reported value |
|---|---|---|---|---|
| BKD BROOKDALE SENIOR LIVING INC | 2,233,741 | 2,575,826 | +15.3% | $41.4M |
| JELD JELD-WEN HOLDING INC | 776,885 | 3,109,621 | +300.3% | $4.7M |
Decreases
| Holding | Shares 2026-03-31 | Shares 2026-06-30 | Change | Reported value |
|---|---|---|---|---|
| NVRI ENVIRI CORP | 4,494,536 | 1,770,959 | -60.6% | $38.9M |
CIK 1218735 · 13F FILINGS ON EDGAR · INFORMATIONAL ONLY
