Mar 31, 2026 filings. Quarterly 13F reports arrive up to 45 days after quarter end; this register is filed through May 29, 2026.
351 institutional managers reported holding OII for the quarter ended Mar 31, 2026. Reported positions total over 95% of shares outstanding; the top 10 hold 61%. 81 opened new positions; 39 closed out. Complete ranked register from SEC 13F filings.
| manager | shares | % out | value (Mar 31, 2026 close) | change | held since |
|---|---|---|---|---|---|
| BlackRock | 16.35M | 16.25% | $580.7M | added +2.2% | ≤2013 |
| Vanguard Group | 12.92M | 12.84% | $459.0M | added +4.3% | ≤2013 |
| Brown Advisory INC | 5.79M | 5.75% | $205.6M | trimmed -22.1% | 2022 Q2 |
| State Street | 5.03M | 5.00% | $178.8M | added +8.3% | ≤2013 |
| Morgan Stanley | 4.49M | 4.47% | $159.6M | trimmed -9.9% | ≤2013 |
| American Century Companies INC | 3.77M | 3.74% | $133.8M | added +4.4% | 2019 Q4 |
| Earnest Partners LLC | 3.68M | 3.66% | $130.9M | trimmed -2.8% | 2022 Q4 |
| Dimensional Fund Advisors | 3.46M | 3.44% | $123.0M | unchanged | ≤2013 |
| Neuberger Berman Group LLC | 3.22M | 3.20% | $114.3M | trimmed -3.5% | 2020 Q4 |
| Geode Capital | 2.38M | 2.36% | $84.4M | added +3.1% | ≤2013 |
| VAN ECK Associates CORP | 2.06M | 2.05% | $73.2M | added +37.4% | ≤2013 |
| Greenhouse Funds Lllp (focused) | 2.03M | 2.02% | $72.2M | trimmed -17.7% | 2022 Q2 |
| Loomis Sayles & CO L P | 1.70M | 1.69% | $60.4M | trimmed -7.2% | 2023 Q3 |
| Barrow Hanley Mewhinney & Strauss LLC | 1.42M | 1.41% | $50.5M | opened | 2026 Q1 |
| Charles Schwab Investment Management | 1.38M | 1.38% | $49.1M | trimmed -4.1% | ≤2013 |
| T. Rowe Price | 1.30M | 1.29% | $46.0M | added +1178.5% | ≤2013 |
| Northern Trust | 1.27M | 1.26% | $45.0M | added +4.2% | ≤2013 |
| Royal Bank OF Canada | 1.05M | 1.04% | $37.2M | trimmed -14.2% | ≤2013 |
| Goldman Sachs | 999.9k | 0.99% | $35.5M | trimmed -21.5% | ≤2013 |
| Boston Partners | 854.9k | 0.85% | $30.4M | opened | 2026 Q1 |
| Franklin Resources | 828.4k | 0.82% | $29.4M | added +85.6% | ≤2013 |
| Ranger Investment Management, L.p. | 796.6k | 0.79% | $28.3M | trimmed -0.8% | 2024 Q2 |
| Fisher Investments | 792.3k | 0.79% | $28.1M | unchanged | ≤2013 |
| BNY Mellon | 755.3k | 0.75% | $26.8M | trimmed -1.9% | ≤2013 |
| Goehring & Rozencwajg Associates, LLC (focused) | 713.6k | 0.71% | $25.3M | added +25.5% | 2022 Q4 |
| Invesco | 701.7k | 0.70% | $24.9M | added +17.5% | ≤2013 |
| Old West Investment Management, LLC | 697.2k | 0.69% | $24.8M | added +28.3% | 2024 Q4 |
| Federated Hermes, INC. | 688.2k | 0.68% | $24.4M | added +526.2% | ≤2013 |
| MFS Investment Management | 681.6k | 0.68% | $24.2M | opened | 2026 Q1 |
| UBS | 615.4k | 0.61% | $21.9M | trimmed -17.8% | ≤2013 |
| Schroder Investment Management Group | 604.2k | 0.60% | $21.5M | added +20.4% | 2020 Q1 |
| Qube Research & Technologies LTD | 588.3k | 0.58% | $20.9M | trimmed -49.5% | 2023 Q1 |
| Principal Financial Group INC | 585.4k | 0.58% | $20.8M | added +1.5% | ≤2013 |
| Fort Washington Investment Advisors INC /OH/ | 526.0k | 0.52% | $18.7M | trimmed -38.6% | 2024 Q2 |
| Boston Trust Walden CORP | 519.5k | 0.52% | $18.5M | trimmed -2.4% | 2025 Q2 |
| Panagora Asset Management INC | 482.8k | 0.48% | $17.1M | added +25.7% | ≤2013 |
| Algert Global LLC | 452.9k | 0.45% | $16.1M | trimmed -35.3% | 2023 Q1 |
| SEI Investments CO | 440.7k | 0.44% | $15.7M | added +5.2% | ≤2013 |
| First Trust Advisors LP | 435.2k | 0.43% | $15.5M | trimmed -22.6% | 2023 Q2 |
| Nuveen | 435.1k | 0.43% | $15.5M | trimmed -37.9% | 2019 Q2 |
| AQR Capital | 392.1k | 0.39% | $13.9M | added +5.2% | ≤2013 |
| Storebrand Asset Management AS | 366.2k | 0.36% | $13.0M | opened | 2026 Q1 |
| AGF Management LTD | 365.9k | 0.36% | $13.0M | trimmed -2.3% | 2025 Q4 |
| Public Sector Pension Investment Board | 357.0k | 0.35% | $12.7M | added +3.4% | 2019 Q4 |
| FMR (Fidelity) | 345.5k | 0.34% | $12.3M | added +28.1% | ≤2013 |
| Keating Investment Counselors INC | 338.4k | 0.34% | $12.0M | trimmed -4.5% | 2022 Q2 |
| Gamco Investors, INC. et al | 338.3k | 0.34% | $12.0M | trimmed -1% | ≤2013 |
| Granite Investment Partners, LLC | 327.1k | 0.33% | $11.6M | added +37.2% | 2025 Q4 |
| BNP Paribas Financial Markets | 325.1k | 0.32% | $11.5M | added +4% | ≤2013 |
| Barclays PLC | 298.7k | 0.30% | $10.6M | trimmed -28.3% | ≤2013 |
Largest 50 of 351 shown; the full ranked, searchable register is at boothcheck.com/holders/OII. 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.