ATS CORP (ATS) Institutional Shareholders
ATS CORP (ATS) is currently reported in institutional portfolios tracked by InsiderSet based on the latest available SEC Form 13F filings for the quarter ended June 30, 2026. The institutional investors covered on this page collectively reported approximately $2.22B in ATS holdings during the latest filing period.
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 $333.17M, representing an estimated loss of -29.43% since the filing period.
The top 10 institutional shareholders tracked on this page collectively account for approximately 64% 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
137
Total Reported Value
$2.22B
Largest Holder
Mason Capital Management Llc
Largest Position
$472.11M
Insider Transactions (90d)
0
Latest Filing Quarter
Q2 2026
New Institutional Positions
119
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 | $333,168,693 | -$138,943,320 | -29.43% | |
| Royal Bank Of Canada | 0.04% | 7,881,423 | $226,828,000 | $160,071,701 | -$66,756,299 | -29.43% | |
| Edgepoint Investment Group Inc. | 1.52% | 7,004,577 | $201,699,483 | $142,262,959 | -$59,436,524 | -29.47% | |
| Turtle Creek Asset Management | Andrew Brenton | 3.47% | 3,084,567 | $88,773,838 | $62,647,556 | -$26,126,282 | -29.43% |
| Bank Of Montreal | 0.03% | 3,062,973 | $88,199,482 | $62,208,982 | -$25,990,500 | -29.47% | |
| Fmr Llc | 0.00% | 2,905,456 | $83,747,606 | $59,009,811 | -$24,737,795 | -29.54% | |
| Fairfax Financial Holdings | Prem Watsa | 2.67% | 2,486,400 | $70,487,018 | $50,498,784 | -$19,988,234 | -28.36% |
| Vanguard Capital Management Llc | 0.00% | 2,398,431 | $69,132,375 | $48,712,134 | -$20,420,241 | -29.54% | |
| Janus Henderson Group Plc | 0.03% | 2,297,214 | $64,543,983 | $46,656,416 | -$17,887,567 | -27.71% | |
| Hill City Capital, Lp | 1.21% | 1,649,857 | $47,482,884 | $33,508,596 | -$13,974,288 | -29.43% | |
| Td Waterhouse Canada Inc. | 0.12% | 1,683,683 | $47,430,639 | $34,195,602 | -$13,235,037 | -27.90% | |
| Ack Asset Management Llc | 5.04% | 1,500,000 | $43,170,000 | $30,465,000 | -$12,705,000 | -29.43% | |
| Fil Ltd | 0.03% | 1,326,851 | $38,235,591 | $26,948,344 | -$11,287,247 | -29.52% | |
| Alberta Investment Management Corp | 0.20% | 1,177,491 | $33,903,767 | $23,914,842 | -$9,988,925 | -29.46% | |
| Scheer, Rowlett & Associates Investment Management Ltd. | 2.43% | 1,175,268 | $33,842,293 | $23,869,693 | -$9,972,600 | -29.47% | |
| Van Lanschot Kempen Investment Management N.V. | 0.25% | 795,619 | $32,524,905 | $16,159,022 | -$16,365,883 | -50.32% | |
| Bank Of America Corp | 0.00% | 1,122,152 | $32,295,534 | $22,790,907 | -$9,504,627 | -29.43% | |
| Connor, Clark & Lunn Investment Management Ltd. | 0.06% | 1,089,460 | $31,371,419 | $22,126,933 | -$9,244,486 | -29.47% | |
| Norges Bank | 0.00% | 1,084,181 | $31,219,408 | $22,019,716 | -$9,199,692 | -29.47% | |
| Clearbridge Investments, Llc | 0.03% | 1,060,487 | $30,520,820 | $21,538,491 | -$8,982,329 | -29.43% | |
| Legal & General Group Plc | 0.01% | 1,056,408 | $30,403,319 | $21,455,646 | -$8,947,673 | -29.43% | |
| Td Asset Management Inc | 0.03% | 1,003,596 | $28,917,712 | $20,383,035 | -$8,534,677 | -29.51% | |
| Marathon Asset Management Ltd | 1.12% | 954,485 | $27,500,179 | $19,385,590 | -$8,114,589 | -29.51% | |
| National Bank Of Canada | 0.02% | 855,316 | $24,208,177 | $17,371,468 | -$6,836,709 | -28.24% | |
| Mirae Asset Global Etfs Holdings Ltd. | 0.03% | 788,784 | $22,728,099 | $16,020,203 | -$6,707,896 | -29.51% | |
| Massachusetts Financial Services Co | 0.01% | 540,733 | $22,105,165 | $10,982,287 | -$11,122,878 | -50.32% | |
| Mackenzie Financial Corp | 0.02% | 524,774 | $21,452,761 | $10,658,160 | -$10,794,601 | -50.32% | |
| Vanguard Fiduciary Trust Co | 0.00% | 724,271 | $20,876,387 | $14,709,944 | -$6,166,443 | -29.54% | |
| Langdon Equity Partners | 9.66% | 600,000 | $17,286,631 | $12,186,000 | -$5,100,631 | -29.51% | |
| Toronto Dominion Bank | 0.02% | 406,916 | $11,717,237 | $8,264,464 | -$3,452,773 | -29.47% | |
| Public Sector Pension Investment Board | 0.03% | 378,001 | $10,884,684 | $7,677,200 | -$3,207,484 | -29.47% | |
| 1832 Asset Management L.P. | 0.01% | 355,745 | $10,238,341 | $7,225,181 | -$3,013,160 | -29.43% | |
| Waratah Capital Advisors Ltd. | 0.74% | 334,923 | $9,639,084 | $6,802,286 | -$2,836,798 | -29.43% | |
| Cibc World Market Inc. | 0.02% | 327,087 | $9,419,737 | $6,643,137 | -$2,776,600 | -29.48% | |
| Arrowmark Colorado Holdings Llc | 0.34% | 280,000 | $8,058,400 | $5,686,800 | -$2,371,600 | -29.43% | |
| Vanguard Global Advisers, Llc | 0.00% | 274,103 | $7,900,745 | $5,567,032 | -$2,333,713 | -29.54% | |
| Roubaix Capital, Llc | 2.55% | 246,909 | $7,106,041 | $5,014,722 | -$2,091,319 | -29.43% | |
| Charles Schwab Investment Management Inc | 0.00% | 243,525 | $7,016,953 | $4,945,993 | -$2,070,960 | -29.51% | |
| Sixth Street Partners Management Company, L.P. | 0.00% | 243,525 | $7,016,953 | $4,945,993 | -$2,070,960 | -29.51% | |
| Morgan Stanley | 0.00% | 234,236 | $6,741,322 | $4,757,333 | -$1,983,989 | -29.43% | |
| Goldman Sachs Group Inc | 0.00% | 223,762 | $6,439,870 | $4,544,606 | -$1,895,264 | -29.43% | |
| Ubs Group Ag | 0.00% | 222,553 | $6,405,076 | $4,520,051 | -$1,885,025 | -29.43% | |
| Dixon Mitchell Investment Counsel Inc. | 0.20% | 211,025 | $6,080,495 | $4,285,918 | -$1,794,577 | -29.51% | |
| Scotia Capital Inc. | 0.02% | 212,719 | $6,021,550 | $4,320,323 | -$1,701,227 | -28.25% | |
| Jane Street Group, Llc | 0.00% | 199,635 | $5,748,858 | $4,054,587 | -$1,694,271 | -29.47% | |
| Granite Investment Partners, Llc | 0.29% | 195,894 | $5,637,829 | $3,978,607 | -$1,659,222 | -29.43% | |
| Focus Partners Wealth | 0.01% | 181,975 | $5,237,241 | $3,695,912 | -$1,541,329 | -29.43% | |
| First Trust Advisors Lp | 0.00% | 181,592 | $5,234,254 | $3,688,134 | -$1,546,120 | -29.54% | |
| Swiss National Bank | 0.00% | 168,000 | $4,828,346 | $3,412,080 | -$1,416,266 | -29.33% | |
| Dimensional Fund Advisors Lp | 0.00% | 167,149 | $4,808,370 | $3,394,796 | -$1,413,574 | -29.40% |
Frequently asked questions about ATS
Who owns the most ATS stock?
The largest holders of ATS are typically major institutional investors such as asset managers and hedge funds reporting on Form 13F. The table above ranks tracked superinvestors by reported position size using the latest available filings for ATS CORP (ATS).
Is ATS widely held by superinvestors?
Many widely followed stocks like ATS appear across numerous superinvestor portfolios because of liquidity, index inclusion, and fundamentals. The holder count and table above show how broadly ATS is represented among the institutional managers we track.
What do “Current Estimated Value”, “Gain/loss Since Filing”, and “Estimated Portfolio Performance” mean?
Current Estimated Value is reported share quantity from the latest 13F times our most recent split-adjusted U.S. session close. Gain/loss Since Filing is that estimate minus the reported 13F dollar value; Estimated Portfolio Performance is that difference as a percent of the reported value. Green means the estimate is above the filing value; red means below (not purchase cost). If many filers share the same implied filing price per share, the performance % may match across rows. These are not official fund marks or live quotes.