MASON CAPITAL MANAGEMENT LLC

NEW YORK, NY · CIK 1218735 · 13F filing filed 2024-08-14

SEC-registered investment adviser since 2012 · limited liability company

Assets managed$2.2bn
Staff15 · 10 in investment roles
Main clients (by assets)Private funds 100%
Private funds3 (2 hedge) · $2.8bn gross assets
Websitemasoncap.com
Form ADV · 2026-03-31SEC adviser record

Legal entityMASON CAPITAL MANAGEMENT LLC (US)

$538.2m reported value -26.1% vs Q1 2024

6positions

100.0%in top 10

1 new 1 added 0 reduced 1 sold out vs Q1 2024

Holdings, Q2 2024

The small lines show how much was held over the last 4 quarters (adjusted for stock splits).

#	Security	Ticker	Shares	Value	% of portfolio	Change	Shares change
1	ATS CORPORATION COM ATS	ATS	14,349,765	$463.6m86.14%	86.14%	Unchanged
2	BARNES GROUP INC COM B	B	1,050,079	$43.5m8.08%	8.08%	Added +260.0k	+259,957 32.9%
3	CLEAR CHANNEL OUTDOOR HLDGS COM CCO	CCO	9,828,401	$13.9m2.57%	2.57%	Unchanged
4	VERADIGM INC COM MDRX	MDRX	938,238	$8.9m1.66%	1.66%	Unchanged
5	I3 VERTICALS INC COM CL A IIIV	IIIV	337,099	$7.4m1.38%	1.38%	New
6	SIGNATURE BK NEW YORK N Y COM SBNY	SBNY	400,000	$876.0k0.16%	0.16%	Unchanged

Sold out since Q1 2024

Security	Ticker	Shares held before	Value then
SEADRILL LTD SDRL	SDRL	398,629	$20.1m398.6k shares

Stakes above 5%

Companies where this manager has reported owning more than 5% of a class of shares, on Schedule 13D (may seek influence) or 13G (passive): its latest filing for each, from 19 Dec 2024 on.

Company	Ticker	Stake	Change	Schedule	Last filed
VERADIGM INC MDRX · 13G · filed 2026-01-29	MDRX	5.8%	new	13G	2026-01-29
JELD-WEN HLDG INC JELD · 13G · filed 2026-08-05	JELD	5.5%≈ $7.2m	new	13G	2026-08-05