Mar 31, 2026 filings. Quarterly 13F reports arrive up to 45 days after quarter end; this register is filed through May 29, 2026.
536 institutional managers reported holding RMBS for the quarter ended Mar 31, 2026. Together they hold about 92% of shares outstanding; the top 10 hold 51%. 76 opened new positions; 82 closed out. Complete ranked register from SEC 13F filings.
| manager | shares | % out | value (Mar 31, 2026 close) | change | held since |
|---|---|---|---|---|---|
| BlackRock | 16.31M | 14.86% | $1.40B | unchanged | ≤2013 |
| Vanguard Group | 12.42M | 11.32% | $1.07B | added +0.8% | ≤2013 |
| Invesco | 6.50M | 5.92% | $558.5M | added +56.7% | ≤2013 |
| State Street | 4.37M | 3.99% | $375.8M | added +2.9% | ≤2013 |
| T. Rowe Price | 3.38M | 3.08% | $290.2M | trimmed -37.3% | 2021 Q1 |
| FMR (Fidelity) | 3.32M | 3.02% | $285.2M | added +109.1% | 2021 Q1 |
| Geode Capital | 3.12M | 2.85% | $268.5M | added +9.9% | ≤2013 |
| T. Rowe Price Investment Management, INC. | 2.39M | 2.18% | $205.5M | added +10173.8% | 2025 Q2 |
| EdgePoint Investment Group INC. (focused) | 1.95M | 1.77% | $167.4M | added +38.5% | 2025 Q1 |
| Dimensional Fund Advisors | 1.80M | 1.64% | $154.3M | trimmed -5.2% | ≤2013 |
| Swedbank Robur | 1.56M | 1.43% | $134.3M | added +14.7% | 2023 Q1 |
| Bank OF America CORP /DE/ | 1.36M | 1.24% | $117.0M | added +9% | ≤2013 |
| Northern Trust | 1.33M | 1.22% | $114.6M | added +1.4% | ≤2013 |
| Charles Schwab Investment Management | 1.33M | 1.21% | $114.0M | unchanged | ≤2013 |
| Neuberger Berman Group LLC | 1.30M | 1.19% | $111.9M | unchanged | ≤2013 |
| Congress Asset Management CO | 1.28M | 1.16% | $109.6M | trimmed -9.5% | 2024 Q4 |
| AQR Capital | 1.25M | 1.14% | $107.5M | added +75.8% | 2018 Q1 |
| Morgan Stanley | 1.21M | 1.11% | $104.3M | added +37.1% | ≤2013 |
| UBS | 1.20M | 1.09% | $102.9M | added +71% | ≤2013 |
| Barclays PLC | 1.10M | 1.00% | $94.2M | added +7.1% | ≤2013 |
| Bessemer Group INC | 1.04M | 0.95% | $89.4M | added +1009.5% | 2023 Q1 |
| Citigroup INC | 1.01M | 0.92% | $86.6M | added +100.5% | ≤2013 |
| Ameriprise Financial INC | 975.2k | 0.89% | $83.8M | added +72.1% | ≤2013 |
| Goldman Sachs | 922.1k | 0.84% | $79.2M | trimmed -22.8% | ≤2013 |
| Nuveen | 892.3k | 0.81% | $76.7M | trimmed -19% | 2019 Q2 |
| Wellington Management | 856.6k | 0.78% | $73.6M | trimmed -8.3% | 2017 Q3 |
| Raymond James Financial INC | 791.0k | 0.72% | $68.0M | trimmed -15.2% | 2023 Q1 |
| BNY Mellon | 779.9k | 0.71% | $67.0M | trimmed -28.7% | ≤2013 |
| Voya Investment Management LLC | 765.8k | 0.70% | $65.8M | added +5.7% | ≤2013 |
| Rafferty Asset Management, LLC | 745.5k | 0.68% | $64.1M | trimmed -20.3% | 2025 Q3 |
| Fisher Investments | 738.4k | 0.67% | $63.4M | added +42.7% | 2025 Q3 |
| Hood River Capital Management LLC | 727.5k | 0.66% | $62.5M | added +2.6% | 2025 Q1 |
| PointState Capital LP (focused) | 701.3k | 0.64% | $60.3M | opened | 2026 Q1 |
| Loomis Sayles & CO L P | 659.8k | 0.60% | $56.7M | trimmed -5.8% | 2025 Q2 |
| Clearbridge Investments, LLC | 583.3k | 0.53% | $50.1M | opened | 2026 Q1 |
| Oberweis Asset Management INC/ | 526.3k | 0.48% | $45.2M | added +13.9% | 2024 Q4 |
| Emerald Advisers, LLC | 493.2k | 0.45% | $42.4M | trimmed -21.3% | 2023 Q1 |
| Caisse de depot et placement du Quebec | 448.6k | 0.41% | $38.5M | unchanged | 2025 Q2 |
| Panagora Asset Management INC | 436.4k | 0.40% | $37.5M | unchanged | 2022 Q2 |
| Schwartz Investment Counsel INC | 420.3k | 0.38% | $36.1M | added +133.1% | 2025 Q1 |
| Stephens Investment Management Group LLC | 407.8k | 0.37% | $35.0M | added +110.5% | 2023 Q3 |
| Lord, Abbett & CO. LLC | 387.1k | 0.35% | $33.3M | trimmed -28.2% | 2025 Q1 |
| Principal Financial Group INC | 373.5k | 0.34% | $32.1M | trimmed -9.3% | ≤2013 |
| Westwood Holdings Group INC | 369.1k | 0.34% | $31.7M | added +29.5% | 2021 Q4 |
| Janus Henderson | 358.9k | 0.33% | $30.8M | trimmed -5.4% | 2021 Q3 |
| Champlain Investment Partners, LLC | 357.2k | 0.33% | $30.7M | opened | 2026 Q1 |
| SEI Investments CO | 339.9k | 0.31% | $29.2M | trimmed -12.1% | 2014 Q1 |
| Shannon River Fund Management LLC (focused) | 333.8k | 0.30% | $28.7M | opened | 2026 Q1 |
| Nomura Asset Management International INC. | 326.9k | 0.30% | $28.1M | added +50.8% | 2025 Q3 |
| Franklin Resources | 323.4k | 0.29% | $27.8M | trimmed -33.4% | 2022 Q4 |
Largest 50 of 536 shown; the full ranked, searchable register is at boothcheck.com/holders/RMBS. 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.