account_balance

Investment manager · 13F filer · SEC CIK 1218735

Mason Capital Management LLC

Reported value$607Mas of Jun 30, 2026
Positions9 2 new, 0 sold out
Top 10 weight100.0%ATS alone is 78%
FiledAug 1445 days after quarter end

Portfolio · as of Jun 30, 2026

Where the money is

New or addedTrimmedHeld

This fund reports 9 stocks.

Box size is the share of the fund. 13F only covers US-listed stocks, so foreign holdings and short positions are missing.

Show the top 9 as a list
ATS Ats Corporation 77.8% HeldBKD Brookdale Senior Living Inc 6.8% Added +15%
Enviri Corp 6.4% Trimmed −61%
CCO Clear Channel Outdoor Hldgs 3.9% Held
GRPN Groupon Inc 2.6% NewRC Ready Capital Corp 1.2% HeldJELD Jeld-wen Holding Inc 0.8% Added +300%
Contextlogic Holdings Inc 0.4% New
SBNY Signature Bank 0.0% Held

What changed

Biggest moves since Mar 31, 2026

Filed Aug 14, 2026, compared with the May 15, 2026 filing
add_circleNew
  • GRPN $15.8M
  • Contextlogic Holdings Inc $2.59M
arrow_upwardAdded
arrow_downwardTrimmed
  • Enviri Corp −61%
remove_circleSold out

None

Where this data comes from. Insider trades, fund holdings, activist stakes and company results come from public SEC EDGAR filings (Forms 4, 13F, 13D/13G, 10-Q and 8-K). Congress trades come from the STOCK Act reports members file with the House Clerk and the Senate.

This is data, not investment advice. About StockToast