Mar 31, 2026 filings. Quarterly 13F reports arrive up to 45 days after quarter end; this register is filed through May 29, 2026.
290 institutional managers reported holding ATKR for the quarter ended Mar 31, 2026. Together they hold about 95% of shares outstanding; the top 10 hold 49%. 43 opened new positions; 59 closed out. Complete ranked register from SEC 13F filings.
| manager | shares | % out | value (Mar 31, 2026 close) | change | held since |
|---|---|---|---|---|---|
| Vanguard Group | 3.89M | 11.46% | $228.9M | added +7% | 2016 Q3 |
| Gates Capital Management, INC. (focused) | 2.69M | 7.91% | $158.0M | trimmed -1.7% | 2022 Q3 |
| BlackRock | 2.63M | 7.74% | $154.5M | added +2.8% | 2016 Q3 |
| American Century Companies INC | 1.44M | 4.24% | $84.7M | added +14.8% | 2018 Q2 |
| Dimensional Fund Advisors | 1.23M | 3.62% | $72.2M | added +8.6% | 2017 Q3 |
| First Trust Advisors LP | 1.23M | 3.61% | $72.2M | trimmed -11.5% | 2017 Q1 |
| LSV Asset Management | 1.05M | 3.10% | $61.9M | added +9.5% | 2018 Q1 |
| Coliseum Capital Management, LLC (focused) | 947.1k | 2.79% | $55.7M | added +17% | 2025 Q4 |
| Geode Capital | 854.7k | 2.52% | $50.3M | added +6.5% | 2016 Q3 |
| State Street | 835.2k | 2.46% | $49.1M | added +0.9% | 2016 Q3 |
| Earnest Partners LLC | 777.9k | 2.29% | $45.8M | trimmed -0.7% | 2025 Q4 |
| Hill City Capital, LP (focused) | 728.2k | 2.14% | $42.8M | unchanged | 2025 Q3 |
| Harding Loevner LP | 704.9k | 2.08% | $41.5M | trimmed -3.8% | 2024 Q2 |
| Arrowstreet Capital | 698.1k | 2.06% | $41.1M | trimmed -0.9% | 2025 Q2 |
| Mirae Asset Global Etfs Holdings LTD. | 533.0k | 1.57% | $31.4M | added +51.7% | 2018 Q3 |
| Bank OF America CORP /DE/ | 462.3k | 1.36% | $27.2M | added +10.1% | 2016 Q2 |
| Charles Schwab Investment Management | 417.6k | 1.23% | $24.6M | added +1.6% | 2016 Q3 |
| Gendell Jeffrey L | 400.2k | 1.18% | $23.5M | added +3.4% | 2024 Q3 |
| Victory Capital Management INC | 379.3k | 1.12% | $22.3M | trimmed -23% | 2017 Q1 |
| London CO OF Virginia | 377.6k | 1.11% | $22.2M | trimmed -8.3% | 2025 Q1 |
| Oslo Pensjonsforsikring AS | 377.0k | 1.11% | $22.2M | opened | 2026 Q1 |
| Two Sigma | 353.0k | 1.04% | $20.8M | added +60.9% | 2022 Q4 |
| NEW York State Common Retirement Fund | 343.5k | 1.01% | $20.2M | trimmed -0.7% | 2016 Q2 |
| Jacobs Levy Equity Management, INC | 343.3k | 1.01% | $20.2M | added +6% | 2025 Q3 |
| Morgan Stanley | 338.3k | 1.00% | $19.9M | trimmed -14.7% | 2016 Q2 |
| Northern Trust | 321.4k | 0.95% | $18.9M | trimmed -11.6% | 2016 Q3 |
| Canyon Capital (focused) | 305.0k | 0.90% | $17.9M | opened | 2026 Q1 |
| Swedbank Robur | 296.2k | 0.87% | $17.4M | unchanged | 2023 Q4 |
| Goldman Sachs | 276.1k | 0.81% | $16.2M | trimmed -28.1% | 2016 Q2 |
| CPP Investment Board | 247.2k | 0.73% | $14.5M | trimmed -24.9% | 2021 Q1 |
| Bridgeway Capital Management, LLC | 244.2k | 0.72% | $14.4M | added +5.4% | 2025 Q3 |
| BNY Mellon | 235.9k | 0.69% | $13.9M | unchanged | 2016 Q3 |
| SEI Investments CO | 208.5k | 0.61% | $12.3M | added +1.2% | 2018 Q2 |
| Nuveen | 193.9k | 0.57% | $11.4M | unchanged | 2019 Q2 |
| Allianz Asset Management GmbH | 184.2k | 0.54% | $10.8M | added +86.6% | 2018 Q4 |
| UBS | 183.5k | 0.54% | $10.8M | added +20.7% | 2016 Q2 |
| Wells Fargo & COMPANY/MN | 178.0k | 0.52% | $10.5M | trimmed -11.7% | 2016 Q3 |
| DNB Asset Management AS | 166.6k | 0.49% | $9.8M | added +14% | 2024 Q2 |
| Federated Hermes, INC. | 159.6k | 0.47% | $9.4M | added +3.3% | 2016 Q2 |
| Barclays PLC | 158.8k | 0.47% | $9.3M | added +156.7% | 2016 Q4 |
| Deutsche Bank AG\ | 156.1k | 0.46% | $9.2M | added +136.6% | 2016 Q3 |
| Hotchkis & Wiley Capital Management LLC | 153.5k | 0.45% | $9.0M | trimmed -1.4% | 2025 Q1 |
| Man Group | 150.3k | 0.44% | $8.8M | added +146.3% | 2018 Q1 |
| Qube Research & Technologies LTD | 147.0k | 0.43% | $8.6M | added +72.6% | 2019 Q4 |
| Empowered Funds, LLC | 133.5k | 0.39% | $7.9M | added +8.3% | 2021 Q2 |
| Healthcare OF Ontario Pension Plan Trust Fund | 125.8k | 0.37% | $7.4M | added +99.7% | 2025 Q3 |
| PDT Partners | 116.2k | 0.34% | $6.8M | added +3039.7% | 2025 Q4 |
| Woodline Partners LP | 102.1k | 0.30% | $6.0M | opened | 2026 Q1 |
| Invesco | 94.3k | 0.28% | $5.6M | trimmed -9.1% | 2017 Q1 |
| Russell Investments Group, LTD. | 94.3k | 0.28% | $5.5M | added +12.6% | 2016 Q4 |
Largest 50 of 290 shown; the full ranked, searchable register is at boothcheck.com/holders/ATKR. Related filers are grouped using the filings' own included-manager declarations. Historically, several managers opening new positions in the same quarter said almost nothing about the quarter that followed (59,118 cases since 2013). A filed record, not a forecast. Nothing here is investment advice.