Who owns Rambus (RMBS)
Which tracked institutional funds hold RMBS, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See RMBS company fundamentals →
Ownership as of the 2026-Q2 13F filings (latest filed 2026-09-22). 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.
How the tape is positioned
264 tracked funds added or opened RMBS while 101 trimmed or exited it between 2026-Q1 and 2026-Q2 — the tape is split. When large holders disagree on a name, the funds moving first are sometimes ahead of the story.
A prompt to read the filings, not a verdict. 13F is a quarter-end snapshot disclosed up to 45 days late; a fund adds or exits for mandate, benchmark, and timing reasons that have nothing to do with a view on the stock. This is a starting question, not a signal to trade.
Conviction spread
RMBS’s largest tracked holder by dollar value, BlackRock, Inc., sizes it at 0.0% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 0.0pp gap the other way — the median holder sizes RMBS more heavily than its largest holder by dollar value does.
Book-share is each fund’s reported value in RMBS divided by its whole reported 13F book, so it is comparable across funds of different sizes and is unaffected by stock splits. A higher share means a fund has committed more of its book to the name — a starting question about conviction, not a verdict or a signal to trade.
Institutional & insider positioning
Between 2026-Q1 and 2026-Q2, across 571 tracked filers holding RMBS, 305 increased or opened the position and 322 reduced or closed it; over the same quarter, open-market insider Form 4s were net sales.
This fuses two public signals for the same quarter — how tracked institutions changed their positions and whether insiders bought or sold in the open market. It describes what was filed; it is a starting question, not a verdict or a signal to trade.
New buyers & exits
Funds opening or closing a position in RMBS between the 2026-Q1 and 2026-Q2 13F filings, and the largest changes among funds holding it in both. New buyers and exits are counted on fund presence (split-invariant); adds and trims are measured on reported value.
New buyers 59
- Nykredit A/S$54M
- Maple Rock Capital Partners Inc.$45M
- Jupiter Topco LLC$38M
- GILDER GAGNON HOWE & CO LLC$34M
- WILLIAM BLAIR INVESTMENT MANAGEMENT, LLC$27M
- Duquesne Family Office LLC$23M
Full exits 52
- T. Rowe Price Investment Management, Inc.$206M
- BESSEMER GROUP INC$89M
- Hood River Capital Management LLC$63M
- LORD, ABBETT & CO. LLC$33M
- JANUS HENDERSON GROUP PLC$31M
- HighTower Advisors, LLC$16M
Largest adds
- FMR LLC$1.1B
- BlackRock, Inc.$615M
- Invesco Ltd.$339M
- VANGUARD PORTFOLIO MANAGEMENT LLC$234M
- VANGUARD CAPITAL MANAGEMENT LLC$232M
- PRICE T ROWE ASSOCIATES INC /MD/$152M
Largest trims
- VOYA INVESTMENT MANAGEMENT LLC$53M
- AMERIPRISE FINANCIAL INC$41M
- PANAGORA ASSET MANAGEMENT INC$36M
- UBS Group AG$33M
- EdgePoint Investment Group Inc.$23M
- SCHWARTZ INVESTMENT COUNSEL INC$23M
Institutional holders
One row per tracked fund, most shares held first (every row is from one quarter; reported value breaks ties). “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding.
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| BlackRock, Inc. trimmed | 13,964,477 | $1.9B | 15.2% | 2026-Q2 |
| FMR LLC added | 10,460,026 | $1.4B | 11.4% | 2026-Q2 |
| Invesco Ltd. added | 6,632,458 | $880M | 7.2% | 2026-Q2 |
| VANGUARD PORTFOLIO MANAGEMENT LLC trimmed | 6,068,516 | $806M | 6.6% | 2026-Q2 |
| VANGUARD CAPITAL MANAGEMENT LLC added | 4,874,385 | $647M | 5.3% | 2026-Q2 |
| STATE STREET CORP trimmed | 3,915,113 | $519M | 4.2% | 2026-Q2 |
| PRICE T ROWE ASSOCIATES INC /MD/ trimmed | 3,334,512 | $443M | 3.6% | 2026-Q2 |
| GEODE CAPITAL MANAGEMENT, LLC trimmed | 2,297,660 | $305M | 2.5% | 2026-Q2 |
| JPMORGAN CHASE & CO added | 2,101,418 | $261M | 2.1% | 2026-Q2 |
| DIMENSIONAL FUND ADVISORS LP trimmed | 1,719,400 | $228M | 1.9% | 2026-Q2 |
| Swedbank AB added | 1,646,500 | $219M | 1.8% | 2026-Q2 |
| NORGES BANK trimmed | 1,532,622 | $203M | 1.7% | 2026-Q2 |
| MORGAN STANLEY added | 1,444,281 | $192M | 1.6% | 2026-Q2 |
| NEUBERGER BERMAN GROUP LLC added | 1,311,777 | $173M | 1.4% | 2026-Q2 |
| BANK OF AMERICA CORP /DE/ trimmed | 1,218,726 | $162M | 1.3% | 2026-Q2 |
| AQR CAPITAL MANAGEMENT LLC trimmed | 1,211,009 | $152M | 1.2% | 2026-Q2 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC trimmed | 1,109,132 | $147M | 1.2% | 2026-Q2 |
| EdgePoint Investment Group Inc. trimmed | 1,086,213 | $144M | 1.2% | 2026-Q2 |
| Rafferty Asset Management, LLC added | 984,388 | $131M | 1.1% | 2026-Q2 |
| GOLDMAN SACHS GROUP INC added | 960,878 | $128M | 1.0% | 2026-Q2 |
| NORTHERN TRUST CORP trimmed | 949,113 | $126M | 1.0% | 2026-Q2 |
| Bank of New York Mellon Corp added | 828,233 | $110M | 0.9% | 2026-Q2 |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE added | 797,195 | $106M | 0.9% | 2026-Q2 |
| CONGRESS ASSET MANAGEMENT CO trimmed | 777,993 | $103M | 0.8% | 2026-Q2 |
| PointState Capital LP added | 764,172 | $101M | 0.8% | 2026-Q2 |
| D. E. Shaw & Co., Inc. added | 739,701 | $98M | 0.8% | 2026-Q2 |
| Fisher Asset Management, LLC trimmed | 705,847 | $94M | 0.8% | 2026-Q2 |
| VANGUARD FIDUCIARY TRUST CO trimmed | 699,213 | $93M | 0.8% | 2026-Q2 |
| BARCLAYS PLC trimmed | 645,970 | $86M | 0.7% | 2026-Q2 |
| RAYMOND JAMES FINANCIAL INC trimmed | 603,874 | $80M | 0.7% | 2026-Q2 |
| Clearbridge Investments, LLC added | 589,641 | $78M | 0.6% | 2026-Q2 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP added | 555,935 | $74M | 0.6% | 2026-Q2 |
| CITIGROUP INC trimmed | 532,402 | $71M | 0.6% | 2026-Q2 |
| OBERWEIS ASSET MANAGEMENT INC/ added | 527,016 | $70M | 0.6% | 2026-Q2 |
| Nuveen, LLC trimmed | 496,422 | $66M | 0.5% | 2026-Q2 |
| MILLENNIUM MANAGEMENT LLC added | 472,818 | $63M | 0.5% | 2026-Q2 |
| LOOMIS SAYLES & CO L P trimmed | 470,934 | $63M | 0.5% | 2026-Q2 |
| PRINCIPAL FINANCIAL GROUP INC added | 429,951 | $57M | 0.5% | 2026-Q2 |
| WELLINGTON MANAGEMENT GROUP LLP trimmed | 418,533 | $56M | 0.5% | 2026-Q2 |
| Stephens Investment Management Group LLC added | 409,436 | $54M | 0.4% | 2026-Q2 |
| Nykredit A/S new | 406,702 | $54M | 0.4% | 2026-Q2 |
| CITADEL ADVISORS LLC added | 400,151 | $53M | 0.4% | 2026-Q2 |
| WESTFIELD CAPITAL MANAGEMENT CO LP added | 385,811 | $51M | 0.4% | 2026-Q2 |
| UBS Group AG trimmed | 373,590 | $50M | 0.4% | 2026-Q2 |
| Maple Rock Capital Partners Inc. new | 342,600 | $45M | 0.4% | 2026-Q2 |
| CANADA PENSION PLAN INVESTMENT BOARD added | 330,648 | $44M | 0.4% | 2026-Q2 |
| AMERIPRISE FINANCIAL INC trimmed | 321,195 | $43M | 0.3% | 2026-Q2 |
| Champlain Investment Partners, LLC trimmed | 299,368 | $40M | 0.3% | 2026-Q2 |
| RHUMBLINE ADVISERS trimmed | 296,916 | $39M | 0.3% | 2026-Q2 |
| Shannon River Fund Management LLC trimmed | 291,713 | $39M | 0.3% | 2026-Q2 |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC added | 289,022 | $38M | 0.3% | 2026-Q2 |
| Jupiter Topco LLC new | 288,553 | $38M | 0.3% | 2026-Q2 |
| Caisse de depot et placement du Quebec trimmed | 282,580 | $38M | 0.3% | 2026-Q2 |
| NOMURA ASSET MANAGEMENT INTERNATIONAL INC. trimmed | 271,982 | $36M | 0.3% | 2026-Q2 |
| TimesSquare Capital Management, LLC trimmed | 267,705 | $36M | 0.3% | 2026-Q2 |
| SEI INVESTMENTS CO trimmed | 261,830 | $35M | 0.3% | 2026-Q2 |
| WESTWOOD HOLDINGS GROUP INC trimmed | 260,065 | $35M | 0.3% | 2026-Q2 |
| FIRST TRUST ADVISORS LP trimmed | 258,308 | $34M | 0.3% | 2026-Q2 |
| GILDER GAGNON HOWE & CO LLC new | 257,434 | $34M | 0.3% | 2026-Q2 |
| EMERALD ADVISERS, LLC trimmed | 252,693 | $34M | 0.3% | 2026-Q2 |
| Allianz Asset Management GmbH added | 243,202 | $28M | 0.2% | 2026-Q2 |
| MACKENZIE FINANCIAL CORP added | 242,194 | $32M | 0.3% | 2026-Q2 |
| California Public Employees Retirement System added | 230,004 | $31M | 0.2% | 2026-Q2 |
| TWO SIGMA INVESTMENTS, LP added | 222,921 | $30M | 0.2% | 2026-Q2 |
| BNP PARIBAS FINANCIAL MARKETS trimmed | 220,814 | $29M | 0.2% | 2026-Q2 |
| Swiss National Bank added | 217,000 | $29M | 0.2% | 2026-Q2 |
| VICTORY CAPITAL MANAGEMENT INC added | 208,063 | $28M | 0.2% | 2026-Q2 |
| WILLIAM BLAIR INVESTMENT MANAGEMENT, LLC trimmed | 200,116 | $27M | 0.2% | 2026-Q2 |
| Tidal Investments LLC added | 180,833 | $24M | 0.2% | 2026-Q2 |
| Ranger Investment Management, L.P. trimmed | 176,692 | $23M | 0.2% | 2026-Q2 |
| Duquesne Family Office LLC new | 173,000 | $23M | 0.2% | 2026-Q2 |
| ROYAL BANK OF CANADA added | 169,479 | $22M | 0.2% | 2026-Q2 |
| VAN ECK ASSOCIATES CORP added | 167,993 | $22M | 0.2% | 2026-Q2 |
| Russell Investments Group, Ltd. added | 162,179 | $22M | 0.2% | 2026-Q2 |
| SEGALL BRYANT & HAMILL, LLC added | 160,293 | $21M | 0.2% | 2026-Q2 |
| TUDOR INVESTMENT CORP ET AL added | 157,155 | $21M | 0.2% | 2026-Q2 |
| ALLIANCEBERNSTEIN L.P. trimmed | 155,136 | $13M | 0.1% | 2026-Q2 |
| Mirae Asset Global Investments Co., Ltd. added | 154,872 | $21M | 0.2% | 2026-Q2 |
| Legal & General Group Plc trimmed | 153,857 | $20M | 0.2% | 2026-Q2 |
| LOS ANGELES CAPITAL MANAGEMENT LLC added | 150,204 | $20M | 0.2% | 2026-Q2 |
| Driehaus Capital Management LLC trimmed | 144,875 | $19M | 0.2% | 2026-Q2 |
| Retirement Systems of Alabama added | 141,345 | $19M | 0.2% | 2026-Q2 |
| EMERALD MUTUAL FUND ADVISERS TRUST trimmed | 139,275 | $18M | 0.2% | 2026-Q2 |
| OSAIC HOLDINGS, INC. trimmed | 137,170 | $18M | 0.1% | 2026-Q2 |
| WCM INVESTMENT MANAGEMENT, LLC trimmed | 130,986 | $16M | 0.1% | 2026-Q2 |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM added | 125,421 | $17M | 0.1% | 2026-Q2 |
| MUTUAL OF AMERICA CAPITAL MANAGEMENT LLC trimmed | 121,491 | $16M | 0.1% | 2026-Q2 |
| Creative Planning added | 120,191 | $16M | 0.1% | 2026-Q2 |
| ASSETMARK, INC trimmed | 119,875 | $16M | 0.1% | 2026-Q2 |
| NORDEA INVESTMENT MANAGEMENT AB trimmed | 104,479 | $13M | 0.1% | 2026-Q2 |
| VANGUARD ASSET MANAGEMENT, Ltd added | 103,541 | $14M | 0.1% | 2026-Q2 |
| DF DENT & CO INC added | 102,771 | $14M | 0.1% | 2026-Q2 |
| NOMURA HOLDINGS INC added | 101,062 | $13M | 0.1% | 2026-Q2 |
| SCHWARTZ INVESTMENT COUNSEL INC trimmed | 100,000 | $13M | 0.1% | 2026-Q2 |
| VOYA INVESTMENT MANAGEMENT LLC trimmed | 99,762 | $13M | 0.1% | 2026-Q2 |
| Rockefeller Capital Management L.P. added | 96,045 | $13M | 0.1% | 2026-Q2 |
| JANE STREET GROUP, LLC added | 95,013 | $13M | 0.1% | 2026-Q2 |
| Y-Intercept (Hong Kong) Ltd added | 94,680 | $13M | 0.1% | 2026-Q2 |
| STATE OF WISCONSIN INVESTMENT BOARD trimmed | 94,192 | $13M | 0.1% | 2026-Q2 |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. trimmed | 94,035 | $12M | 0.1% | 2026-Q2 |
Ownership over time
Tracked institutional holder count and total shares held by filing quarter (independent scales). The curated-era tail and any mid-ingest latest quarter are handled honestly — a partial quarter is not drawn as a collapse.
Reading this table
Funds hold the same stock for different reasons — an index fund “holds” almost everything, an active manager sizes a name to a mandate and a benchmark, and each fund entered at its own price and time. Because 13F is filed up to 45 days after quarter-end, every row is a backward-looking snapshot; a manager may have traded since. Share-class siblings (a company’s A and C shares) are rolled up to one line so a dual-class name is never double-counted. Compare like-for-like. A large holder is not an endorsement, and a fund exiting is not a warning — this is a starting question, not a verdict.
About 13F filings
A Form 13F is a quarterly disclosure that institutional investment managers with over $100 million in US-listed equities must file with the SEC. In plain English: it is a snapshot of the long stock positions a fund held at the end of a quarter. It covers long US-listed equities only — not short positions, options, cash, or private holdings — and the funds shown are the large sample we track, not the complete 13F universe.