Ranked by reported Q1 2026 13F market value
Share of total reported institutional value in RMBS held by the largest 10 / 25 filers.
| # | Institution | Shares Held | Market Value | QoQ Change | Ownership % | % of Fund |
|---|---|---|---|---|---|---|
| 1 | BlackRock, Inc. | 16.3M | $1.40B | +0.2% | 15.075% | 0.02% |
| 2 | VANGUARD PORTFOLIO MANAGEMENT LLC | 6.6M | $571.6M | β | 6.143% | 0.03% |
| 3 | Invesco Ltd. | 6.5M | $559.1M | +56.6% | 6.009% | 0.09% |
| 4 | VANGUARD CAPITAL MANAGEMENT LLC | 4.8M | $415.3M | β | 4.464% | 0.01% |
| 5 | STATE STREET CORP | 4.4M | $376.3M | +2.9% | 4.044% | 0.01% |
| 6 | FMR LLC | 3.3M | $285.5M | +109.1% | 3.068% | 0.02% |
| 7 | GEODE CAPITAL MANAGEMENT, LLC | 3.1M | $268.8M | +9.9% | 2.889% | 0.02% |
| 8 | EdgePoint Investment Group Inc. | 1.9M | $167.6M | +38.5% | 1.801% | 1.34% |
| 9 | DIMENSIONAL FUND ADVISORS LP | 1.8M | $154.4M | -5.2% | 1.660% | 0.03% |
| 10 | Swedbank AB | 1.6M | $134.5M | +14.7% | 1.445% | 0.14% |
| 11 | BANK OF AMERICA CORP /DE/ | 1.4M | $117.1M | +9.0% | 1.259% | 0.01% |
| 12 | NORTHERN TRUST CORP | 1.3M | $114.8M | +1.4% | 1.234% | 0.02% |
| 13 | CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 1.3M | $114.1M | -0.1% | 1.226% | 0.02% |
| 14 | Neuberger Berman Group LLC | 1.3M | $111.7M | -0.3% | 1.204% | 0.09% |
| 15 | CONGRESS ASSET MANAGEMENT CO /MA | 1.3M | $109.8M | -9.5% | 1.180% | 0.79% |
| 16 | MORGAN STANLEY | 1.2M | $104.4M | +37.1% | 1.122% | 0.01% |
| 17 | AQR CAPITAL MANAGEMENT LLC | 1.3M | $104.0M | +75.8% | 1.156% | 0.05% |
| 18 | BARCLAYS PLC | 1.1M | $94.3M | +7.1% | 1.013% | 0.04% |
| 19 | CITIGROUP INC | 1.0M | $86.7M | +100.5% | 0.931% | 0.04% |
| 20 | AMERIPRISE FINANCIAL INC | 975K | $83.9M | +72.1% | 0.902% | 0.02% |
| 21 | UBS Group AG | 973K | $83.7M | +113.5% | 0.899% | 0.01% |
| 22 | GOLDMAN SACHS GROUP INC | 922K | $79.3M | -22.8% | 0.852% | 0.01% |
| 23 | Nuveen, LLC | 892K | $76.8M | -19.0% | 0.825% | 0.02% |
| 24 | WELLINGTON MANAGEMENT GROUP LLP | 857K | $73.7M | -8.3% | 0.792% | 0.01% |
| 25 | Bank of New York Mellon Corp | 780K | $67.1M | -28.7% | 0.721% | 0.01% |
denotes a marquee investor (Buffett, Burry, ARK, Tiger Global, Pershing Square, Baupost and other widely-followed managers). β% of Fundβ shows how much of that investorβs total 13F portfolio is invested in RMBS β a direct measure of their conviction.
Filings activity in RMBS during Q1 2026, grouped by how each filer changed its position.
Institutions that opened a new RMBS position in Q1 2026
Institutions that fully closed their RMBS position in Q1 2026
8 quarters of 13F filings Β· Ξ columns show change vs prior quarter
| Quarter | Inst. Holders | Ξ Holders | Ownership % | Ξ Ownership | Total 13F Value | Ξ Value |
|---|---|---|---|---|---|---|
| Q1 2026 | 541 | +0.2% | 50.00% | 3.58 pp | $7.93B | 6.7% |
| Q4 2025 | 540 | +8.2% | 53.58% | 6.89 pp | $8.49B | 11% |
| Q3 2025 | 499 | +11% | 60.47% | +23.76 pp | $9.59B | +65% |
| Q2 2025 | 448 | +11% | 36.71% | +8.15 pp | $5.82B | +29% |
| Q1 2025 | 403 | +5.8% | 28.56% | 0.26 pp | $4.53B | 0.9% |
| Q4 2024 | 381 | +3.8% | 28.82% | +5.70 pp | $4.57B | +25% |
| Q3 2024 | 367 | +2.8% | 23.12% | 10.96 pp | $3.66B | 32% |
| Q2 2024 | 357 | β | 34.08% | β | $5.40B | β |
Source: SEC 13F institutional filings. Ownership % requires market cap data and will show once linked. Ξ columns compare to the immediately prior filed quarter.
Quick answers to the most common questions about buying RMBS stock.
Based on Q1 2026 13F filings, institutional ownership of Rambus Inc. stands at 50.0%, held across 541 reporting institutions.
BlackRock, Inc. is the largest reported institutional holder of RMBS, with approximately 16,305,306 shares worth $1.40B as of Q1 2026.
No marquee "smart money" managers (Berkshire, Burry, ARK, Tiger Global, Pershing Square, Baupost, etc.) currently appear among the top 25 institutional holders of RMBS.
Our composite Smart Money Score for RMBS is 27 out of 100 (Bearish). It combines net institutional buying activity, ownership shift, marquee investor presence, and holder-count growth.
89 institutions opened new positions in RMBS during Q1 2026, while 88 fully exited. 123 added to existing positions and 325 trimmed.
RMBS institutional ownership fell by 3.58 percentage points quarter-over-quarter, with a net change of +1 holders.
The top 10 institutions account for 54.7% of all reported 13F value in RMBS, and the top 25 account for 72.6%.
All data is sourced from SEC Form 13F filings, which institutional investment managers with at least $100M in assets are required to file each quarter. We process every 13F filing from EDGAR and recompute the aggregates after each cycle. Insider transactions are sourced from Form 4 filings.
Rambus Inc. (RMBS) Institutional Ownership