Managers / Q1 2026
MASON CAPITAL MANAGEMENT LLC
CIK 0001218735 · 110 EAST 59TH STREET, 30TH FLOOR, NEW YORK, NY, 10022 · 2127711206
Reported Value
$613M
Q1 2026
Positions
7
Filings on Record
31
2019–present window
Filed
May 15, 2026
original filing
Summary
Mason Capital Management Llc reported $613M in U.S.-listed holdings across 7 positions for Q1 2026.
The portfolio is heavily concentrated: ATS alone accounts for 75.5% of reported value.
Compared with Q4 2025, the fund opened 2 new positions and exited 4.
Reported Value by Quarter
13F Reported Value
Portfolio Composition
By security type
Composition data arrives with ticker enrichment.
Quarter-over-Quarter Changes full breakdown →
Holdings — Q1 2026
Filing History
| Quarter | Reported Value | Positions | Filed | Type | Links |
|---|---|---|---|---|---|
| Q1 2026 | $613M | 7 | May 15, 2026 | 13F-HR | changes · EDGAR ↗ |
| Q4 2025 | $562M | 9 | Feb 17, 2026 | 13F-HR | changes · EDGAR ↗ |
| Q3 2025 | $491M | 6 | Nov 14, 2025 | 13F-HR | changes · EDGAR ↗ |
| Q2 2025 | $512M | 4 | Aug 14, 2025 | 13F-HR | changes · EDGAR ↗ |
| Q1 2025 | $427M | 5 | May 15, 2025 | 13F-HR | changes · EDGAR ↗ |
| Q4 2024 | $471M | 4 | Feb 14, 2025 | 13F-HR | changes · EDGAR ↗ |
| Q3 2024 | $503M | 6 | Nov 14, 2024 | 13F-HR | changes · EDGAR ↗ |
| Q2 2024 | $538M | 6 | Aug 14, 2024 | 13F-HR | changes · EDGAR ↗ |
| Q1 2024 | $728M | 6 | May 15, 2024 | 13F-HR | changes · EDGAR ↗ |
| Q4 2023 | $894M | 7 | Feb 15, 2024 | 13F-HR | changes · EDGAR ↗ |
| Q3 2023 | $1.2B | 8 | Nov 14, 2023 | 13F-HR | changes · EDGAR ↗ |
| Q2 2023 | $1.0B | 10 | Aug 14, 2023 | 13F-HR | changes · EDGAR ↗ |
| Q1 2023 | $234M | 12 | May 15, 2023 | 13F-HR | changes · EDGAR ↗ |
| Q4 2022 | $609.2B | 13 | Feb 14, 2023 | 13F-HR | changes · EDGAR ↗ |
| Q3 2022 | $258M | 12 | Nov 14, 2022 | 13F-HR | changes · EDGAR ↗ |
| Q2 2022 | $309M | 18 | Aug 15, 2022 | 13F-HR | changes · EDGAR ↗ |
| Q1 2022 | $313M | 16 | May 16, 2022 | 13F-HR | changes · EDGAR ↗ |
| Q4 2021 | $209M | 7 | Feb 14, 2022 | 13F-HR | changes · EDGAR ↗ |
| Q3 2021 | $1.4B | 37 | Nov 15, 2021 | 13F-HR | changes · EDGAR ↗ |
| Q2 2021 | $1.6B | 34 | Aug 16, 2021 | 13F-HR | changes · EDGAR ↗ |
| Q1 2021 | $438M | 24 | May 17, 2021 | 13F-HR | changes · EDGAR ↗ |
| Q4 2020 | $1.2B | 18 | Feb 16, 2021 | 13F-HR | changes · EDGAR ↗ |
| Q3 2020 | $1.1B | 8 | Nov 13, 2020 | 13F-HR | changes · EDGAR ↗ |
| Q2 2020 | $1.0B | 10 | Aug 14, 2020 | 13F-HR | changes · EDGAR ↗ |
| Q1 2020 | $314M | 11 | May 15, 2020 | 13F-HR | changes · EDGAR ↗ |
| Q4 2019 | $291M | 8 | Feb 14, 2020 | 13F-HR | changes · EDGAR ↗ |
| Q3 2019 | $410M | 9 | Nov 14, 2019 | 13F-HR | changes · EDGAR ↗ |
| Q2 2019 | $524M | 10 | Aug 14, 2019 | 13F-HR | changes · EDGAR ↗ |
| Q1 2019 | $465M | 8 | May 15, 2019 | 13F-HR | changes · EDGAR ↗ |
| Q4 2018 | $2.6B | 12 | Feb 14, 2019 | 13F-HR | changes · EDGAR ↗ |
13F filings are due up to 45 days after quarter end, so holdings shown here lag the fund’s current book. Source: original SEC filing on EDGAR ↗.