Mason Capital Management LLC: 13F holdings, Q2 2026
Hedge fund · SEC EDGAR filings (CIK 1218735) · Explore on the interactive board
Mason Capital Management LLC disclosed 9 US equity positions worth $607.0m in its Q2 2026 13F filing (holdings as of June 30, 2026, filed August 14, 2026). Its largest position is ATS at 77.8% of the reported book, followed by BKD, NVRI. The top ten holdings are 100.0% of the book, and the portfolio behaves like about 2 equal-weight positions. Versus the prior filing it opened 2 new positions, added to 2, reduced 1 and exited 0. Note: this manager's most recent filing is 3934 quarters behind the newest quarter on file, so these figures are history rather than current positioning.
What does Mason Capital Management LLC own? Top holdings as of June 30, 2026
Change is measured in shares against the previous filing (Q1 2026), so price moves do not read as decisions. This quarter: 2 new, 2 added, 1 reduced, 0 exited.
| # | Stock | Sector | Weight | Value | Shares | Δ shares | Action |
|---|---|---|---|---|---|---|---|
| 1 | ATS ATS CORPORATION | Industrials | 77.8% | $472.1m | 16,404,170 | 0% | held |
| 2 | BKD BROOKDALE SENIOR LIVING INC | Healthcare | 6.8% | $41.4m | 2,575,826 | 15% | added |
| 3 | NVRI ENVIRI CORP | Industrials | 6.4% | $38.9m | 1,770,959 | -61% | reduced |
| 4 | CCO CLEAR CHANNEL OUTDOOR HLDGS | Communication Services | 3.9% | $23.8m | 9,828,401 | 0% | held |
| 5 | GRPN GROUPON INC | Communication Services | 2.6% | $15.8m | 657,144 | – | new |
| 6 | RC READY CAPITAL CORP | 1.2% | $7.6m | 4,319,933 | 0% | held | |
| 7 | JELD JELD-WEN HOLDING INC | Industrials | 0.8% | $4.7m | 3,109,621 | 300% | added |
| 8 | CONTEXTLOGIC HOLDINGS INC | 0.4% | $2.6m | 291,341 | – | new | |
| 9 | SBNY SIGNATURE BANK | Financial Services | 0.0% | $180.0k | 400,000 | 0% | held |
Sector mix
| Sector | Weight |
|---|---|
| Industrials | 84.9% |
| Healthcare | 6.8% |
| Communication Services | 6.5% |
| Financial Services | 0.0% |
Sectors cover positions whose ticker resolved to a sector; the remainder is unclassified, not cash.
Filing history
How concentrated is Mason Capital Management LLC's portfolio?
Across every quarter Mason Capital Management LLC has filed, its median largest position is 76.6% of the book and its median top-ten weight is 100.0%, which WhaleCreep classifies as concentrated (the gate is a median largest position of 5%).