MASON CAPITAL MANAGEMENT LLC
CIK 1218735 · Holdings on Jun 30, 2026 · First reported Aug 14, 2026
Top ten holdings
Q2 2026- ATS77.78%
- BKD6.83%
- 4158641076.40%
- CCO3.92%
- GRPN2.60%
- RC1.25%
- JELD0.77%
- LOGC0.43%
- SBNY0.03%
Share classes counted separately100.01%
Portfolio value by quarter
What changed this quarter?
Within preview · weight change- 415864107Weight decreased · -7.99 pp14.39% → 6.40%Shares -2.72M (-60.60%)
- ATSWeight increased · +2.30 pp75.48% → 77.78%Shares 0 (0.00%)
- BKDWeight increased · +1.84 pp4.99% → 6.83%Shares +342.08K (+15.31%)
Weight = security value ÷ total reported holdings value. Changes are in percentage points; price moves also affect weights, so they are not trade sizes.
Top 10 holdings 9
USD · B = billion · M = million; expand a row for exact values| # | Security | Value | Weight | Quantity | Weight / quantity change | Activity | |
|---|---|---|---|---|---|---|---|
| 01 | ATSATS CORP View history and evidence | $472.11M | 77.78% | 16.40M shares | 75.48% → 77.78%+2.30 pp 0 (0.00%) | Unchanged | ▾ |
| 02 | BKDBROOKDALE SENIOR LIVING INC View history and evidence | $41.45M | 6.83% | 2.58M shares | 4.99% → 6.83%+1.84 pp +342.08K (+15.31%) | Added | ▾ |
| 03 | 415864107ENVIRI CORP View history and evidence | $38.87M | 6.40% | 1.77M shares | 14.39% → 6.40%-7.99 pp -2.72M (-60.60%) | Reduced | ▾ |
| 04 | CCOCLEAR CHANNEL OUTDOOR HOLDIN View history and evidence | $23.78M | 3.92% | 9.83M shares | 3.80% → 3.92%+0.12 pp 0 (0.00%) | Unchanged | ▾ |
| 05 | GRPNGROUPON INC View history and evidence | $15.81M | 2.60% | 657.14K shares | Prior unavailable +657.14K | New | ▾ |
| 06 | RCREADY CAPITAL CORPREIT View history and evidence | $7.56M | 1.25% | 4.32M shares | 1.14% → 1.25%+0.11 pp 0 (0.00%) | Unchanged | ▾ |
| 07 | JELDJELD-WEN HOLDING INC View history and evidence | $4.66M | 0.77% | 3.11M shares | 0.16% → 0.77%+0.61 pp +2.33M (+300.27%) | Added | ▾ |
| 08 | LOGCCONTEXTLOGIC HOLDINGS INC View history and evidence | $2.59M | 0.43% | 291.34K shares | Prior unavailable +291.34K | New | ▾ |
| 09 | SBNYSIGNATURE BANK View history and evidence | $180.00K | 0.03% | 400.00K shares | 0.04% → 0.03%-0.01 pp 0 (0.00%) | Unchanged | ▾ |
Options overlay 0
No options reported this quarter.
Exited positions 0
No exits reported this quarter.
Every number has a source.
CIK 1218735 · Period 2026-06-30
Data loaded 2026-09-23 · First reported 2026-08-14
Amendments and versions
{
"amendments_merged": null,
"prior_versions": null,
"cover_table_value": 607022468
}Take these holdings further.
This page includes 9 of 9 reported holdings. Sign in to look up the full history beyond 3 years, use advanced screening & filtering, download CSV, and get the complete set through the Akkru API.
- Download CSV
- Earlier quarters
- Advanced screening & filtering
- API & AI access
＋ New accounts get free API credits to explore data beyond ownership filings.
For AI agents & developers
The initial HTML of this page carries its exact data as script#portfolio-data (JSON): values, units, scope, preview limits and SEC sources. Read it directly, no script or API key needed; script#research-access says what needs an account. This page lists 9 of 9 current positions (options included); totals and weights use the complete filing.
Without an account: the last 3 years, with the row caps stated on the page. A free account opens all history on file on these pages and the CSV of what a page shows. Rows beyond the caps and bulk retrieval go through the authenticated API / MCP.
MCP https://api.akkrudata.ai/mcp
get_institutional_portfolio
{"cik":"1218735","quarter":"2026Q2","page_size":100}
get_institutional_manager_history
{"cik":"1218735","page_size":100}Connect to MCP with OAuth and follow the returned pagination. Credits and usage limits depend on the account.
- MCP endpoint
- https://api.akkrudata.ai/mcp
- API / MCP documentation
- /documents
- llms.txt
- /llms.txt
Sources, coverage & how to read this data
Figures are as reported to the SEC and merged with later amendments where Akkru could match them. Preview limits apply to what is listed, not to the totals, which come from the complete reported data. Nothing is zero-filled: a missing quarter or month is shown as missing.