ATS Institutional Ownership & Shareholders
ATS CORP (ATS) is currently held by 134 institutional investors tracked by InsiderSet, with a combined reported market value of approximately $2.30B based on the latest available SEC Form 13F filings for the quarter ended June 30, 2026.
Mason Capital Management Llc is currently the largest disclosed institutional shareholder of ATS tracked by InsiderSet, reporting ownership valued at approximately $472.11M in its June 30, 2026 SEC Form 13F filing. Based on current market prices and the latest disclosed share count, the position is now estimated to be worth approximately $311.19M, representing an estimated loss of -34.09% since the filing period.
The top 10 institutional shareholders tracked on this page collectively account for approximately 65% of the total disclosed ATS value among the investors covered in this analysis. Major shareholders include Mason Capital Management Llc, Royal Bank Of Canada, Edgepoint Investment Group Inc., and several other long-term asset managers with concentrated positions in ATS CORP (ATS).
This page ranks the largest institutional ATS shareholders using publicly disclosed SEC Form 13F data, including reported values, estimated current holding values, portfolio allocation percentages, ownership concentration metrics, and historical holding changes across major hedge funds and investment firms.
Institutional Holders
134
Total Reported Value
$2.30B
Largest Holder
Mason Capital Management Llc
Largest Position
$472.11M
Insider Transactions (90d)
0
Latest Filing Quarter
Q2 2026
New Institutional Positions
110
Funds Exiting Positions
0
| Name | Investor/Manager | Portfolio % | Quantity | Reported Balance | Current Estimated Value | Gain/loss Since Filing | Estimated Portfolio Performance |
|---|---|---|---|---|---|---|---|
| Mason Capital Management Llc | 77.78% | 16,404,170 | $472,112,013 | $311,187,105 | -$160,924,908 | -34.09% | |
| Royal Bank Of Canada | 0.04% | 7,881,423 | $226,828,000 | $149,510,594 | -$77,317,406 | -34.09% | |
| Edgepoint Investment Group Inc. | 1.52% | 7,004,577 | $201,699,483 | $132,876,826 | -$68,822,657 | -34.12% | |
| Beutel, Goodman & Co Ltd. | 1.02% | 4,796,922 | $138,218,000 | $90,997,610 | -$47,220,390 | -34.16% | |
| Turtle Creek Asset Management | Andrew Brenton | 3.47% | 3,084,567 | $88,773,838 | $58,514,236 | -$30,259,602 | -34.09% |
| Bank Of Montreal | 0.03% | 3,062,973 | $88,199,482 | $58,104,598 | -$30,094,884 | -34.12% | |
| Fmr Llc | 0.00% | 2,905,456 | $83,747,606 | $55,116,500 | -$28,631,106 | -34.19% | |
| Fairfax Financial Holdings | Prem Watsa | 2.67% | 2,486,400 | $70,487,018 | $47,167,008 | -$23,320,010 | -33.08% |
| Vanguard Capital Management Llc | 0.00% | 2,398,431 | $69,132,375 | $45,498,236 | -$23,634,139 | -34.19% | |
| Janus Henderson Group Plc | 0.03% | 2,297,214 | $64,543,983 | $43,578,150 | -$20,965,833 | -32.48% | |
| Hill City Capital, Lp | 1.11% | 1,649,857 | $47,482,884 | $31,297,787 | -$16,185,097 | -34.09% | |
| Ack Asset Management Llc | 5.04% | 1,500,000 | $43,170,000 | $28,455,000 | -$14,715,000 | -34.09% | |
| Fil Ltd | 0.03% | 1,326,851 | $38,235,591 | $25,170,363 | -$13,065,228 | -34.17% | |
| Alberta Investment Management Corp | 0.20% | 1,177,491 | $33,903,767 | $22,337,004 | -$11,566,763 | -34.12% | |
| Scheer, Rowlett & Associates Investment Management Ltd. | 2.43% | 1,175,268 | $33,842,293 | $22,294,834 | -$11,547,459 | -34.12% | |
| Van Lanschot Kempen Investment Management N.V. | 0.25% | 795,619 | $32,524,905 | $15,092,892 | -$17,432,013 | -53.60% | |
| Bank Of America Corp | 0.00% | 1,122,152 | $32,295,534 | $21,287,223 | -$11,008,311 | -34.09% | |
| Connor, Clark & Lunn Investment Management Ltd. | 0.06% | 1,089,460 | $31,371,419 | $20,667,056 | -$10,704,363 | -34.12% | |
| Norges Bank | 0.00% | 1,084,181 | $31,219,408 | $20,566,914 | -$10,652,494 | -34.12% | |
| Clearbridge Investments, Llc | 0.03% | 1,060,487 | $30,520,820 | $20,117,438 | -$10,403,382 | -34.09% | |
| Legal & General Group Plc | 0.01% | 1,056,408 | $30,403,319 | $20,040,060 | -$10,363,259 | -34.09% | |
| Td Asset Management Inc | 0.03% | 1,003,596 | $28,917,712 | $19,038,216 | -$9,879,496 | -34.16% | |
| Td Waterhouse Canada Inc. | 0.07% | 1,600,087 | $28,705,627 | $30,353,650 | +$1,648,023 | +5.74% | |
| National Bank Of Canada | 0.02% | 855,316 | $24,208,177 | $16,225,345 | -$7,982,832 | -32.98% | |
| Mirae Asset Global Etfs Holdings Ltd. | 0.03% | 788,784 | $22,728,099 | $14,963,232 | -$7,764,867 | -34.16% | |
| Massachusetts Financial Services Co | 0.01% | 540,733 | $22,105,165 | $10,257,705 | -$11,847,460 | -53.60% | |
| Vanguard Fiduciary Trust Co | 0.00% | 724,271 | $20,876,387 | $13,739,421 | -$7,136,966 | -34.19% | |
| Langdon Equity Partners | 9.66% | 600,000 | $17,286,631 | $11,382,000 | -$5,904,631 | -34.16% | |
| Marathon Asset Management Ltd | 0.60% | 732,044 | $13,261,330 | $13,886,875 | +$625,545 | +4.72% | |
| Toronto Dominion Bank | 0.02% | 406,916 | $11,717,237 | $7,719,197 | -$3,998,040 | -34.12% | |
| Public Sector Pension Investment Board | 0.03% | 378,001 | $10,884,684 | $7,170,679 | -$3,714,005 | -34.12% | |
| 1832 Asset Management L.P. | 0.01% | 355,745 | $10,238,341 | $6,748,483 | -$3,489,858 | -34.09% | |
| Waratah Capital Advisors Ltd. | 0.74% | 334,923 | $9,639,084 | $6,353,489 | -$3,285,595 | -34.09% | |
| Cibc World Market Inc. | 0.02% | 327,087 | $9,419,737 | $6,204,840 | -$3,214,897 | -34.13% | |
| Arrowmark Colorado Holdings Llc | 0.34% | 280,000 | $8,058,400 | $5,311,600 | -$2,746,800 | -34.09% | |
| Vanguard Global Advisers, Llc | 0.00% | 274,103 | $7,900,745 | $5,199,734 | -$2,701,011 | -34.19% | |
| Roubaix Capital, Llc | 2.55% | 246,909 | $7,106,041 | $4,683,864 | -$2,422,177 | -34.09% | |
| Charles Schwab Investment Management Inc | 0.00% | 243,525 | $7,016,953 | $4,619,669 | -$2,397,284 | -34.16% | |
| Mackenzie Financial Corp | 0.01% | 379,755 | $6,861,467 | $7,203,952 | +$342,485 | +4.99% | |
| Morgan Stanley | 0.00% | 234,236 | $6,741,322 | $4,443,457 | -$2,297,865 | -34.09% | |
| Goldman Sachs Group Inc | 0.00% | 223,762 | $6,439,870 | $4,244,765 | -$2,195,105 | -34.09% | |
| Ubs Group Ag | 0.00% | 222,553 | $6,405,076 | $4,221,830 | -$2,183,246 | -34.09% | |
| Dixon Mitchell Investment Counsel Inc. | 0.20% | 211,025 | $6,080,495 | $4,003,144 | -$2,077,351 | -34.16% | |
| Scotia Capital Inc. | 0.02% | 212,719 | $6,021,550 | $4,035,279 | -$1,986,271 | -32.99% | |
| Jane Street Group, Llc | 0.00% | 199,635 | $5,748,858 | $3,787,076 | -$1,961,782 | -34.12% | |
| Granite Investment Partners, Llc | 0.29% | 195,894 | $5,637,829 | $3,716,109 | -$1,921,720 | -34.09% | |
| Van Berkom & Associates Inc. | 0.17% | 188,066 | $5,410,000 | $3,567,612 | -$1,842,388 | -34.06% | |
| Focus Partners Wealth | 0.01% | 181,975 | $5,237,241 | $3,452,066 | -$1,785,175 | -34.09% | |
| First Trust Advisors Lp | 0.00% | 181,592 | $5,234,254 | $3,444,800 | -$1,789,454 | -34.19% | |
| Swiss National Bank | 0.00% | 168,000 | $4,828,346 | $3,186,960 | -$1,641,386 | -33.99% |
Frequently asked questions about ATS
Who are the largest institutional holders of ATS?
The largest institutional holders of ATS reported in the latest SEC Form 13F filings include Mason Capital Management Llc, Royal Bank Of Canada, Edgepoint Investment Group Inc., Beutel, Goodman & Co Ltd., and Turtle Creek Asset Management. InsiderSet ranks institutional holders by their latest reported ATS position.
What is ATS institutional ownership?
This page tracks ATS positions reported by institutional investment managers through SEC Form 13F. ATS CORP (ATS) institutional ownership on InsiderSet reflects disclosed 13F holdings among the managers we analyze, not every shareholder of the stock.
How many institutions own ATS?
InsiderSet currently tracks 134 institutional managers reporting ATS holdings in the latest available 13F data. This count reflects institutions included in the SEC Form 13F filings analyzed by InsiderSet and should not be interpreted as the total number of ATS shareholders.
How much ATS stock do institutions own?
Institutional investment managers disclosed approximately $2.30B in ATS holdings for Q2 2026. This figure is reported 13F value as of the filing period, not necessarily today's market value.
When was ATS institutional ownership last updated?
The latest ATS institutional ownership data on InsiderSet is based on SEC Form 13F filings for the quarter ended June 30, 2026. Form 13F filings are generally reported after the quarter ends, so the holdings shown represent the latest publicly disclosed positions rather than real-time institutional holdings.
Are institutional ATS holdings real-time?
No. Form 13F data is not real-time. It represents positions reported by institutional investment managers as of the end of the reporting quarter. An institution may have changed its ATS position after the reporting date.
Are institutions buying or selling ATS?
Institutional buying and selling can be analyzed by comparing ATS positions across consecutive 13F reporting periods. InsiderSet's ATS Ownership Changes page shows institutions that increased, reduced, initiated, or exited positions based on reported 13F holdings. View ATS ownership changes.
How has ATS institutional ownership changed over time?
InsiderSet tracks ATS institutional holdings across multiple 13F reporting periods, allowing investors to compare institutional holder counts, reported value, and reported shares over time.