MASON CAPITAL MANAGEMENT LLC — 13F Holdings & Portfolio
CIK 1218735 · latest 13F-HR filed 2026-08-14
MASON CAPITAL MANAGEMENT LLC manages $607.0M in 13F-reported U.S. long-equity assets across 9 reported positions as of its 2026-06-30 13F-HR filing. Its largest disclosed positions are ATS (77.78%), BKD (6.83%), NVRI (6.40%). Quarter over quarter (versus its 2026-03-31 filing) the fund opened 2 new positions, exited 0, added to 3, and trimmed 2.
AUM is the long-equity portion reported on Form 13F-HR. Excludes short positions, cash, foreign holdings, and non-13F assets. For informational purposes only — not investment advice.
30TH FLOOR
NEW YORK, NY 10022
$607.0M
Long-equity book
9
Distinct positions
2026-06-30
Filed 2026-08-14
+2 / −0 / ↑3 / ↓2
vs 2026-03-31
| Name | Title / Status | Ownership | Type |
|---|
Top Adds (vs prior quarter)
- BROOKDALE SENIOR LIVING INC$10.9M +35.6%
- JELD-WEN HOLDING INC$3.7M +384.2%
- READY CAPITAL CORP$561.6K +8.0%
Rows tagged Call or Put are options positions, not stock. Per SEC Form 13F-HR, Value shows the notional value of the underlying (shares covered × underlying price), not the option premium. Shares is the number of underlying shares covered (divide by 100 for contract count).
| # | Issuer | Symbol | CUSIP | Value | Weight | Shares | Type |
|---|---|---|---|---|---|---|---|
| 1 | ATS CORPORATION | ATS | 00217Y104 | $472.1M | 77.78% | 16,404,170 | SH |
| 2 | BROOKDALE SENIOR LIVING INC | BKD | 112463104 | $41.4M | 6.83% | 2,575,826 | SH |
| 3 | ENVIRI CORP | NVRI | 415864107 | $38.9M | 6.40% | 1,770,959 | SH |
| 4 | CLEAR CHANNEL OUTDOOR HLDGS | CCO | 18453H106 | $23.8M | 3.92% | 9,828,401 | SH |
| 5 | GROUPON INC | GRPN | 399473206 | $15.8M | 2.60% | 657,144 | SH |
| 6 | READY CAPITAL CORP | RC | 75574U101 | $7.6M | 1.25% | 4,319,933 | SH |
| 7 | JELD-WEN HOLDING INC | JELD | 47580P103 | $4.7M | 0.77% | 3,109,621 | SH |
| 8 | CONTEXTLOGIC HOLDINGS INC | LOGC | 21078F109 | $2.6M | 0.43% | 291,341 | SH |
| 9 | SIGNATURE BANK | BK | 82669G104 | $180.0K | 0.03% | 400,000 | SH |
| Period | Filed | AUM | Holdings | Accession |
|---|---|---|---|---|
| 2026-06-30 | 2026-08-14 | $607.0M | 9 | 0001104659-26-097052 |
| 2026-03-31 | 2026-05-15 | $612.9M | 7 | 0001104659-26-062410 |
| 2025-12-31 | 2026-02-17 | $561.6M | 9 | 0001104659-26-016335 |
| 2025-09-30 | 2025-11-14 | $491.4M | 6 | 0001104659-25-111862 |