Institutional ownership · Form 13F
ATS institutional ownership
ATS Corp /ATS: reported institutional holdings as of 2026-06-30 (filed through 2026-08-31), aggregated by StockEyes from SEC Form 13F information tables. ATS is one of 2732 tickers in the validated publication set. Mapping coverage in this publication set: 4562 of 6046 universe tickers have at least one validated CUSIP mapping (75.5%). Latest-quarter filed value resolved to any listed ticker: 77.3%; resolved to this universe: 77.2%.
ATS: change since the prior quarter's filings
More managers reported a position, with the count rising from 128 in the quarter ended 2026-03-31 to 140 in the quarter ended 2026-06-30 (+12, 9.4%). Total reported shares fell to 81,589,252 (-3,591,281, 4.2%), against the direction of the manager count. Among the 26 managers listed as top holders in both quarters, the largest increases were FMR LLC (+627,984 shares) and Legal & General Group Plc (+444,719 shares), among 10 managers who added shares, and the largest decreases were TURTLE CREEK ASSET MANAGEMENT INC. (-1,812,102 shares) and Connor, Clark & Lunn Investment Management Ltd. (-1,175,297 shares), among 13 managers who reduced shares. Jupiter Topco LLC (2,322,073 shares), NORGES BANK (1,084,181 shares) and 2 more entered the listed top holders; JANUS HENDERSON GROUP PLC (2,297,214 shares in the prior quarter), Vinva Investment Management Ltd (2,088,947 shares in the prior quarter) and 2 more dropped out of the listed top holders.
New to 13F data? Read how to read a 13F filing, or see where institutions moved overall in the Smart Money Report.
Reported totals, quarter ended 2026-06-30
140 reporting managers held 81,589,252 shares, reported value $2,221,808,069 exactly as filed. Values are position values transcribed from the filings, not current market prices.
Reported quarter-over-quarter change (quarter ended 2026-03-31 to quarter ended 2026-06-30): reporting managers +12, reported shares -3,591,281 (-4.22%), reported value +0.35%. These changes compare two filing snapshots.
Shares outstanding check: 96,885,705 shares reported by the issuer (SEC XBRL, period ended 2025-03-31). Reported 13F shares equal 84.2% of that figure. This page passed the publication sanity gate before listing.
ATS in this quarter's filings
Concentration check: the largest reported position, MASON CAPITAL MANAGEMENT LLC with 16,404,170 shares, is 20.1% of all shares reported for ATS this quarter. The five largest reporting managers together account for 45.9% of the reported total, so the headline total is spread across a broad manager base rather than a few holders.
Reported quarter-over-quarter change: the reporting-manager count rose by 12 versus the quarter ended 2026-03-31, and reported shares moved -4.22% (-3,591,281 shares). That is a comparison of two filing snapshots, not a record of trades on any single day.
Shares-outstanding cross-check: reported 13F shares equal 84.2% of the issuer share count used at the publication gate (96,885,705 shares, issuer period ended 2025-03-31). The gate publishes a ticker only when that relationship is plausible; lending chains can push reported totals above a simple ownership share, which is why the figure is a sanity check and not an ownership percentage.
Largest reporting managers, ATS
| # | Manager | Shares | Value as filed | Share of reported total |
|---|---|---|---|---|
| 1 | MASON CAPITAL MANAGEMENT LLC | 16,404,170 | $472,112,013 | 20.1% |
| 2 | ROYAL BANK OF CANADA | 7,881,423 | $226,828,000 | 9.7% |
| 3 | EdgePoint Investment Group Inc. | 7,004,577 | $201,699,483 | 8.6% |
| 4 | TURTLE CREEK ASSET MANAGEMENT INC. | 3,084,567 | $88,773,838 | 3.8% |
| 5 | BANK OF MONTREAL /CAN/ | 3,062,973 | $88,199,482 | 3.8% |
| 6 | FMR LLC | 2,905,456 | $83,747,606 | 3.6% |
| 7 | FAIRFAX FINANCIAL HOLDINGS LTD/ CAN | 2,486,400 | $70,487,018 | 3.0% |
| 8 | VANGUARD CAPITAL MANAGEMENT LLC | 2,398,431 | $69,132,375 | 2.9% |
| 9 | Jupiter Topco LLC | 2,322,073 | $66,907,877 | 2.8% |
| 10 | Hill City Capital, LP | 1,649,857 | $47,482,884 | 2.0% |
| 11 | TD Waterhouse Canada Inc. | 1,683,683 | $47,430,639 | 2.1% |
| 12 | ACK Asset Management LLC | 1,500,000 | $43,170,000 | 1.8% |
| 13 | FIL Ltd | 1,326,851 | $38,235,591 | 1.6% |
| 14 | Alberta Investment Management Corp | 1,177,491 | $33,903,767 | 1.4% |
| 15 | Scheer, Rowlett & Associates Investment Management Ltd. | 1,175,268 | $33,842,293 | 1.4% |
Manager names and figures are transcribed from each manager's own Form 13F information table. A manager listing shares in this snapshot does not mean it holds them today.
Reported change, 2026-03-31 to 2026-06-30
| Quarter ended | Filed through | Reporting managers | Reported shares | Value as filed |
|---|---|---|---|---|
| 2026-03-31 | 2026-05-29 | 128 | 85,180,533 | $2,214,086,407 |
| 2026-06-30 | 2026-08-31 | 140 | 81,589,252 | $2,221,808,069 |
Every change figure on this page is a reported quarter-over-quarter change between filing snapshots. It is not real-time trading activity.
ATS reported totals over time
Quarter ended 2026-06-30: 140 reporting managers · 81,589,252 reported shares · $2,221,808,069 value as filed.
The full archived series is part of StockEyes Pro. Continue with Google to sign in.
Quarter-end 13F filed data, long positions only; filings arrive up to 45 days after quarter end.
CUSIPs behind the ATS total
The validated bridge mapped 1 current CUSIP(s) to ATS for this quarter: 00217Y104. Option pseudo-CUSIPs, units, warrants, and preferred classes are excluded from these common-share totals. Mapping coverage in this publication set: 4562 of 6046 universe tickers have at least one validated CUSIP mapping (75.5%). Latest-quarter filed value resolved to any listed ticker: 77.3%; resolved to this universe: 77.2%.
What this page is and is not
Form 13F reports are quarterly holdings snapshots. Managers file up to about 45 days after quarter-end, so these figures describe reported positions as of the quarter-end date, not holdings today. 13F lists reportable long positions from managers above the SEC reporting threshold and omits short positions entirely.
This page is informational only. It is not investment advice, a recommendation, or a signal to buy or sell. Source: SEC Form 13F bulk data set for filings through 2026-08-31 (period ended 2026-06-30), joined to tickers through StockEyes' validated CUSIP bridge. Methodology and coverage are documented on the institutional ownership hub.
Insider transactions for ATS (officer and director buys and sells) are covered by InsiderTrace: insidertrace.com/stock/ats. StockEyes does not duplicate insider transaction tables.
Related StockEyes pages
Latest headlines tagged ATS are on the market news wire. Upcoming earnings and market dates are on the events calendar. The term itself is defined in the institutional investor glossary entry, and the research workflow behind pages like this one is walked through in how to research a stock and how to compare SEC filings.