Mar 31, 2026 filings. Quarterly 13F reports arrive up to 45 days after quarter end; this register is filed through May 29, 2026.
340 institutional managers reported holding ATMU for the quarter ended Mar 31, 2026. Reported positions total over 95% of shares outstanding; the top 10 hold 48%. 63 opened new positions; 31 closed out. Complete ranked register from SEC 13F filings.
| manager | shares | % out | value (Mar 31, 2026 close) | change | held since |
|---|---|---|---|---|---|
| Vanguard Group | 7.94M | 9.68% | $449.6M | added +1.2% | 2023 Q2 |
| BlackRock | 6.81M | 8.31% | $385.9M | added +0.6% | 2023 Q2 |
| FMR (Fidelity) | 4.94M | 6.02% | $279.8M | added +11.7% | 2023 Q2 |
| T. Rowe Price | 4.49M | 5.47% | $254.2M | trimmed -4.1% | 2023 Q2 |
| Invesco | 3.34M | 4.08% | $189.5M | added +22.6% | 2023 Q4 |
| Goldman Sachs | 3.29M | 4.01% | $186.5M | added +2.8% | 2023 Q2 |
| Geode Capital | 2.65M | 3.23% | $149.9M | added +8.9% | 2023 Q3 |
| First Trust Advisors LP | 2.20M | 2.69% | $124.8M | added +3.3% | 2024 Q2 |
| State Street | 1.90M | 2.31% | $107.4M | unchanged | 2023 Q3 |
| Morgan Stanley | 1.74M | 2.12% | $98.4M | trimmed -18.2% | 2023 Q2 |
| D. E. Shaw | 1.62M | 1.98% | $91.8M | added +12.2% | 2023 Q4 |
| T. Rowe Price Investment Management, INC. | 1.58M | 1.93% | $89.6M | added +2800.2% | 2024 Q4 |
| Janus Henderson | 1.55M | 1.89% | $87.9M | added +13.3% | 2024 Q2 |
| Nuveen | 1.44M | 1.76% | $81.9M | added +10.2% | 2023 Q2 |
| Wellington Management | 1.39M | 1.69% | $78.6M | trimmed -13.5% | 2023 Q2 |
| Channing Capital Management, LLC | 1.39M | 1.69% | $78.5M | trimmed -14.9% | 2025 Q2 |
| Mangrove Partners IM, LLC | 1.32M | 1.60% | $74.5M | unchanged | 2023 Q3 |
| Dimensional Fund Advisors | 1.30M | 1.59% | $73.8M | added +3.6% | 2024 Q2 |
| Eminence Capital (focused) | 1.28M | 1.56% | $72.6M | trimmed -66.5% | 2024 Q3 |
| Westwood Holdings Group INC | 1.24M | 1.51% | $70.2M | trimmed -10.3% | 2025 Q3 |
| Neuberger Berman Group LLC | 1.17M | 1.43% | $66.5M | added +21648.7% | 2024 Q1 |
| Arrowstreet Capital | 999.5k | 1.22% | $56.6M | added +193.8% | 2024 Q1 |
| Charles Schwab Investment Management | 940.6k | 1.15% | $53.3M | added +0.5% | 2023 Q3 |
| Port Capital LLC | 908.7k | 1.11% | $51.5M | added +3.6% | 2025 Q3 |
| Bank OF America CORP /DE/ | 893.6k | 1.09% | $50.6M | added +33.8% | 2023 Q2 |
| Raymond James Financial INC | 821.7k | 1.00% | $46.6M | trimmed -5.1% | 2023 Q2 |
| MFS Investment Management | 818.9k | 1.00% | $46.4M | trimmed -6.7% | 2024 Q1 |
| Parsifal Capital Management, LP (focused) | 789.0k | 0.96% | $44.7M | trimmed -36.1% | 2024 Q1 |
| Royce & Associates | 777.7k | 0.95% | $44.1M | added +16.5% | 2023 Q2 |
| Manufacturers Life Insurance Company, THE | 758.8k | 0.93% | $43.0M | trimmed -1.4% | 2023 Q2 |
| Boston Trust Walden CORP | 750.6k | 0.92% | $42.5M | trimmed -12.1% | 2025 Q4 |
| Frontier Capital Management CO LLC | 742.2k | 0.91% | $42.1M | added +13.6% | 2024 Q3 |
| Qube Research & Technologies LTD | 741.2k | 0.90% | $42.0M | added +121.8% | 2024 Q1 |
| Silvercrest Asset Management Group LLC | 740.6k | 0.90% | $42.0M | trimmed -1.3% | 2025 Q4 |
| Northern Trust | 726.5k | 0.89% | $41.2M | added +1.4% | 2023 Q3 |
| UBS | 515.6k | 0.63% | $29.2M | added +11% | 2023 Q2 |
| Algert Global LLC | 514.9k | 0.63% | $29.2M | trimmed -9.7% | 2024 Q2 |
| Federated Hermes, INC. | 487.3k | 0.59% | $27.6M | added +18% | 2023 Q4 |
| Teacher Retirement System OF Texas | 474.4k | 0.58% | $26.9M | trimmed -19.7% | 2024 Q3 |
| Healthcare OF Ontario Pension Plan Trust Fund | 454.6k | 0.55% | $25.8M | added +752.6% | 2024 Q2 |
| Gw&k Investment Management, LLC | 439.2k | 0.54% | $24.9M | trimmed -9% | 2023 Q4 |
| Jane Street | 426.6k | 0.52% | $24.2M | added +4109% | 2023 Q2 |
| William Blair Investment Management, LLC | 426.1k | 0.52% | $24.1M | trimmed -37.5% | 2025 Q1 |
| Aberdeen Group plc | 372.8k | 0.46% | $21.1M | trimmed -7% | 2024 Q2 |
| NEW York State Common Retirement Fund | 362.2k | 0.44% | $20.5M | trimmed -11.5% | 2023 Q3 |
| BNY Mellon | 359.7k | 0.44% | $20.4M | added +2.5% | 2023 Q3 |
| Woodline Partners LP | 355.9k | 0.43% | $20.2M | added +38.4% | 2025 Q1 |
| Susquehanna International Group | 348.2k | 0.42% | $19.7M | trimmed -21.6% | 2023 Q4 |
| Marshall Wace | 322.6k | 0.39% | $18.3M | trimmed -42.9% | 2024 Q1 |
| Barclays PLC | 308.7k | 0.38% | $17.5M | added +114.8% | 2023 Q3 |
Largest 50 of 340 shown; the full ranked, searchable register is at boothcheck.com/holders/ATMU. 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.