13F Insight
DOSSIER · 13F Holders · Q1 2026
ATS

ATS CORPORATION

149 institutions still hold ATS CORPORATION as of Q1 2026. Tracked across SEC 13F-HR filings, with insider and 13D/G activity surfaced alongside.

CUSIP 00217Y104·149 13F holders·last filed Mar 31, 2026
Market cap
—
13F value held
$1.9B
visible holders
Holders
149
filers reporting
Concentration
24.13%
MASON CAPITAL MANAGEMENT LLC #1
top holder share
AI Holders Summary · Q1 2026

149 institutions reported ATS in Q1 2026. MASON CAPITAL MANAGEMENT LLC leads at 24.1% of the visible book.

Top holders

Sorted by position value. Source: SEC EDGAR 13F-HR filings.

#HolderValueShares% port.Quarter
01
MASON CAPITAL MANAGEMENT LLC
CIK 0001218735
$463M16.4M75.48%Q1 202602
ROYAL BANK OF CANADA
CIK 0001000275
$227M7.9M0.03%Q2 202603
EdgePoint Investment Group Inc.
CIK 0001481669
$202M7.2M1.62%Q1 202604
Beutel, Goodman & Co Ltd.
CIK 0001361974
$153M5.5M1.04%Q1 202605
Turtle Creek Asset Management Inc.
CIK 0001484148
$89M3.1M3.47%Q2 202606
BANK OF MONTREAL /CAN/
CIK 0000927971
$88M3.1M0.03%Q2 202607
FMR LLC
CIK 0000315066
$84M2.9M0.00%Q2 202608
FAIRFAX FINANCIAL HOLDINGS LTD/ CAN
CIK 0000915191
$70M2.5M2.67%Q2 202609
VANGUARD CAPITAL MANAGEMENT LLC
CIK 0002100119· Index
$69M2.4M0.00%Q2 202610
Jupiter Topco LLC
CIK 0002146052
$67M2.3M0.03%Q2 202611
JANUS HENDERSON GROUP PLC
CIK 0001274173
$65M2.3M0.03%Q1 202612
Hill City Capital, LP
CIK 0001837343
$47M1.6M1.11%Q2 202613
TD Waterhouse Canada Inc.
CIK 0001999606
$47M1.7M0.12%Q2 202614
ACK Asset Management LLC
CIK 0001510940
$43M1.5M5.04%Q2 202615
FIL Ltd
CIK 0000318989
$38M1.3M0.03%Q2 202616
Alberta Investment Management Corp
CIK 0001463559· Sovereign
$34M1.2M0.19%Q2 202617
Scheer, Rowlett & Associates Investment Management Ltd.
CIK 0001426327
$34M1.2M2.43%Q2 202618
VAN LANSCHOT KEMPEN INVESTMENT MANAGEMENT N.V.
CIK 0001367401
$33M796K0.25%Q2 202619
BANK OF AMERICA CORP /DE/
CIK 0000070858
$32M1.1M0.00%Q2 202620
Connor, Clark & Lunn Investment Management Ltd.
CIK 0001596800
$31M1.1M0.06%Q2 2026
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