Mar 31, 2026 filings. Quarterly 13F reports arrive up to 45 days after quarter end; this register is filed through May 29, 2026.
356 institutional managers reported holding OSIS for the quarter ended Mar 31, 2026. Reported positions total over 95% of shares outstanding; the top 10 hold 62%. 42 opened new positions; 40 closed out. Complete ranked register from SEC 13F filings.
| manager | shares | % out | value (Mar 31, 2026 close) | change | held since |
|---|---|---|---|---|---|
| BlackRock | 2.53M | 14.63% | $671.0M | trimmed -1.3% | ≤2013 |
| Vanguard Group | 2.08M | 12.05% | $552.8M | trimmed -1.1% | ≤2013 |
| FMR (Fidelity) | 1.97M | 11.38% | $521.8M | added +18.7% | 2018 Q3 |
| Janus Henderson | 772.3k | 4.47% | $204.9M | added +2.6% | 2014 Q1 |
| Mawer Investment Management LTD. | 662.6k | 3.83% | $175.8M | trimmed -17.5% | 2024 Q4 |
| State Street | 662.1k | 3.83% | $175.6M | added +0.6% | ≤2013 |
| Capital International Investors | 619.5k | 3.58% | $164.3M | trimmed -8.1% | 2024 Q4 |
| UBS | 566.5k | 3.28% | $150.3M | trimmed -30.4% | ≤2013 |
| Geode Capital | 440.7k | 2.55% | $116.9M | added +7.2% | ≤2013 |
| Dimensional Fund Advisors | 395.4k | 2.29% | $104.9M | trimmed -2.8% | ≤2013 |
| Invesco | 373.3k | 2.16% | $99.0M | trimmed -12.2% | ≤2013 |
| Hood River Capital Management LLC | 372.1k | 2.15% | $98.7M | trimmed -1.9% | 2023 Q2 |
| Neuberger Berman Group LLC | 303.9k | 1.76% | $80.6M | added +1% | ≤2013 |
| Clark Capital Management Group, INC. | 270.4k | 1.56% | $71.7M | added +1.6% | 2023 Q4 |
| Channing Capital Management, LLC | 266.9k | 1.54% | $70.8M | opened | 2026 Q1 |
| Bank OF America CORP /DE/ | 266.4k | 1.54% | $70.7M | trimmed -6.9% | ≤2013 |
| T. Rowe Price | 259.5k | 1.50% | $68.8M | added +1.8% | ≤2013 |
| PRIMECAP Management | 244.7k | 1.42% | $64.9M | trimmed -8.6% | 2016 Q1 |
| Mirae Asset Global Etfs Holdings LTD. | 232.5k | 1.34% | $61.7M | added +42.5% | 2024 Q2 |
| Systematic Financial Management LP | 219.2k | 1.27% | $58.2M | trimmed -6% | 2018 Q4 |
| Morgan Stanley | 210.4k | 1.22% | $55.8M | trimmed -5.6% | ≤2013 |
| Charles Schwab Investment Management | 201.0k | 1.16% | $53.3M | trimmed -0.5% | ≤2013 |
| Loomis Sayles & CO L P | 191.5k | 1.11% | $50.8M | trimmed -7.7% | 2025 Q1 |
| Neumeier Poma Investment Counsel LLC (focused) | 191.4k | 1.11% | $50.8M | trimmed -2.2% | 2014 Q1 |
| VAN ECK Associates CORP | 188.2k | 1.09% | $49.9M | trimmed -17.1% | 2023 Q1 |
| William Blair Investment Management, LLC | 171.7k | 0.99% | $45.5M | trimmed -10.3% | 2025 Q4 |
| Northern Trust | 170.9k | 0.99% | $45.3M | unchanged | ≤2013 |
| Clearbridge Investments, LLC | 163.6k | 0.95% | $43.4M | trimmed -11.6% | ≤2013 |
| Nomura Asset Management International INC. | 161.5k | 0.93% | $42.8M | trimmed -14.5% | 2025 Q4 |
| Driehaus Capital Management LLC | 118.0k | 0.68% | $31.3M | trimmed -50% | 2025 Q2 |
| Swedbank Robur | 117.7k | 0.68% | $31.2M | added +6.6% | 2024 Q4 |
| Principal Financial Group INC | 108.1k | 0.63% | $28.7M | added +6.5% | ≤2013 |
| BNP Paribas Financial Markets | 107.4k | 0.62% | $28.5M | added +111.8% | 2014 Q2 |
| Oberweis Asset Management INC/ | 106.6k | 0.62% | $28.3M | added +5.1% | 2023 Q3 |
| Envestnet Asset Management INC | 100.4k | 0.58% | $26.6M | added +4.5% | 2021 Q4 |
| BNY Mellon | 98.2k | 0.57% | $26.0M | trimmed -4.6% | ≤2013 |
| Ameriprise Financial INC | 94.1k | 0.54% | $25.0M | added +134.6% | ≤2013 |
| Wellington Management | 93.8k | 0.54% | $24.9M | added +88% | 2025 Q4 |
| Boston Partners | 86.5k | 0.50% | $23.0M | added +12.3% | 2022 Q4 |
| Asset Management One CO., LTD. | 83.3k | 0.48% | $22.1M | added +8.8% | 2014 Q3 |
| Brown Advisory INC | 78.3k | 0.45% | $20.8M | trimmed -48.4% | 2024 Q4 |
| Goldman Sachs | 75.1k | 0.43% | $19.9M | trimmed -30.7% | ≤2013 |
| NEW York State Common Retirement Fund | 71.5k | 0.41% | $19.0M | added +336.4% | ≤2013 |
| Mirova US LLC | 65.0k | 0.38% | $17.2M | opened | 2026 Q1 |
| Nuveen | 59.8k | 0.35% | $15.9M | trimmed -13.5% | 2019 Q2 |
| Public Sector Pension Investment Board | 55.4k | 0.32% | $14.7M | unchanged | ≤2013 |
| American Century Companies INC | 51.0k | 0.29% | $13.5M | added +26.4% | 2020 Q1 |
| Wells Fargo & COMPANY/MN | 50.8k | 0.29% | $13.5M | trimmed -2.2% | ≤2013 |
| Prospect Capital Advisors, LLC (focused) | 49.5k | 0.29% | $13.1M | trimmed -4.8% | 2016 Q2 |
| Nordea Investment Management AB | 45.8k | 0.27% | $12.1M | trimmed -4.9% | 2020 Q1 |
Largest 50 of 356 shown; the full ranked, searchable register is at boothcheck.com/holders/OSIS. 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.