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MASON CAPITAL MANAGEMENT LLC

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13F filer, CIK 1218735, NEW YORK, NY

MASON CAPITAL MANAGEMENT LLC reported $561,604,846 across 9 holdings for the quarter ended 2025-12-31, in a 13F-HR filed 2026-02-17.

Filed (acceptance time not in the bulk data set), ingested 13F-HR 0001104659-26-016335

Period
2025-12-31
Reported value
$562M
Holdings
9
Top 10 weight
100%
New
4
Sold out
1

Largest buys vs the previous quarter

SecurityShares changeApprox. value
SOLSnew+633,801$30.8M
JBSnew+1,306,000$18.8M
BKDadded+1,109,977$12M
BORRnew+2,182,136$8.79M
RCnew+3,776,139$8.23M

Ranked by the share change valued at this quarter's implied price (value over shares in the 13F). A position sold out is valued at the previous quarter's price, its last report.

Largest sells vs the previous quarter

SecurityShares changeApprox. value
KVUEexited-2,595,000-$42.1M

Ranked by the share change valued at this quarter's implied price (value over shares in the 13F). A position sold out is valued at the previous quarter's price, its last report.

Holdings, Q4 2025

Share positions as resolved from 13F-HR 0001104659-26-016335, largest first. % of portfolio is the value over $561,604,846, the sum of the share positions whose value is usable for ratios (method).

SecurityHistorySharesValue% of portfolioChangeLatest eventTimeline
ATSATS CORPORATIONQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 14,914,765 shares; 2024Q4: 14,914,765 shares; 2025Q1: 15,563,568 shares; 2025Q2: 15,563,568 shares; 2025Q3: 15,563,568 shares; 2025Q4: 15,563,568 shares 15,563,568$429M76.32%0Timeline
BKDBROOKDALE SR LIVING INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: 2,475,964 shares; 2025Q4: 3,585,941 shares 3,585,941$38.7M6.89%+1,109,977Timeline
SOLSSOLSTICE ADVANCED MATLS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 633,801 shares 633,801$30.8M5.48%newTimeline
CCOCLEAR CHANNEL OUTDOOR HLDGSQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 9,828,401 shares; 2024Q4: 9,828,401 shares; 2025Q1: 9,828,401 shares; 2025Q2: 9,828,401 shares; 2025Q3: 9,828,401 shares; 2025Q4: 9,828,401 shares 9,828,401$21.7M3.87%0Timeline
JBSJBS N.V.Quarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 1,306,000 shares 1,306,000$18.8M3.35%newTimeline
BORRBORR DRILLING LTDQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 2,182,136 shares 2,182,136$8.79M1.57%newTimeline
RCREADY CAPITAL CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 838,856 shares; 2024Q4: 278,856 shares; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 3,776,139 shares 3,776,139$8.23M1.47%newTimeline
MLABMESA LABS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: 70,300 shares; 2025Q4: 70,300 shares 70,300$5.52M0.98%0Timeline
SBNYSIGNATURE BANKQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 400,000 shares; 2024Q4: 400,000 shares; 2025Q1: 400,000 shares; 2025Q2: 400,000 shares; 2025Q3: 400,000 shares; 2025Q4: 400,000 shares 400,000$404K0.07%0Timeline

Sold out in Q4 2025

Positions in the previous quarter's report that this quarter's report no longer lists.

SecurityShares beforeValue beforeType
KVUEKENVUE INC2,595,000$42.1Mshares

How Q4 2025 was built

Available 13F filings of this filer for the quarter and their roles: the base report is the latest original or restatement, NEW HOLDINGS amendments filed after it are added (method).

FilingRoleAmendmentFiledAcceptedIngested
13F-HR 0001104659-26-016335 base2026-02-17acceptance time not in the bulk data set