Who owns Cabaletta Bio, Inc. (CABA)
Which tracked institutional funds hold CABA, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See CABA company fundamentals →
Ownership as of the 2026-Q1 13F filings (latest filed 2026-05-18). 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
The tracked-fund tape on CABA is one-sided between 2025-Q4 and 2026-Q1: 31 added or opened and 8 trimmed or exited — on balance accumulating.
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
CABA’s largest tracked holder by dollar value, T. Rowe Price Investment Management, 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 conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in CABA 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 2025-Q4 and 2026-Q1, across 108 tracked filers holding CABA, 59 increased or opened the position and 42 reduced or closed it; over the same quarter, open-market insider Form 4s were net purchases.
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 CABA between the 2025-Q4 and 2026-Q1 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 5
- VANGUARD CAPITAL MANAGEMENT LLC$11M
- CANTOR FITZGERALD, L. P.$2M
- VANGUARD FIDUCIARY TRUST CO$2M
- Diametric Capital, LP$707K
- WELLINGTON MANAGEMENT GROUP LLP$666K
Full exits 3
- VANGUARD GROUP INC$10M
- TWO SIGMA ADVISERS, LP$2M
- Ensign Peak Advisors, Inc$1M
Largest adds
- T. Rowe Price Investment Management, Inc.$21M
- MILLENNIUM MANAGEMENT LLC$10M
- Cormorant Asset Management, LP$5M
- Bain Capital Life Sciences Investors, LLC$5M
- JENNISON ASSOCIATES LLC$5M
- Qube Research & Technologies Ltd$4M
Largest trims
- Schonfeld Strategic Advisors LLC$3M
- SUPERSTRING CAPITAL MANAGEMENT LP$2M
- PRICE T ROWE ASSOCIATES INC /MD/$1M
- JANE STREET GROUP, LLC$781K
- XTX Topco Ltd$307K
Institutional holders
One row per tracked fund, largest reported value first. “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding. Rows marked stale are from an earlier filing than the security’s latest quarter — that fund is absent from the newest snapshot (position exited, or reported under a different name).
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| T. Rowe Price Investment Management, Inc. added | 11,080,005 | $30M | 11.6% | 2026-Q1 |
| Bain Capital Life Sciences Investors, LLC | 9,677,125 | $26M | 10.1% | 2026-Q1 |
| JENNISON ASSOCIATES LLC added | 8,970,578 | $24M | 9.4% | 2026-Q1 |
| ADAGE CAPITAL PARTNERS GP, L.L.C. | 8,829,758 | $24M | 9.3% | 2026-Q1 |
| MILLENNIUM MANAGEMENT LLC added | 5,903,281 | $16M | 6.2% | 2026-Q1 |
| Cormorant Asset Management, LP added | 5,500,000 | $15M | 5.8% | 2026-Q1 |
| VANGUARD CAPITAL MANAGEMENT LLC new | 4,028,991 | $11M | 4.2% | 2026-Q1 |
| TWO SIGMA INVESTMENTS, LP added | 2,497,917 | $7M | 2.6% | 2026-Q1 |
| BlackRock, Inc. added | 2,373,003 | $6M | 2.5% | 2026-Q1 |
| MARSHALL WACE, LLP added | 2,179,818 | $6M | 2.3% | 2026-Q1 |
| RENAISSANCE TECHNOLOGIES LLC added | 2,036,663 | $5M | 2.1% | 2026-Q1 |
| Qube Research & Technologies Ltd added | 1,934,990 | $5M | 2.0% | 2026-Q1 |
| MORGAN STANLEY added | 1,408,152 | $4M | 1.5% | 2026-Q1 |
| Opaleye Management Inc. added | 1,380,000 | $4M | 1.4% | 2026-Q1 |
| Woodline Partners LP | 1,250,242 | $3M | 1.3% | 2026-Q1 |
| GEODE CAPITAL MANAGEMENT, LLC added | 1,133,245 | $3M | 1.2% | 2026-Q1 |
| SUPERSTRING CAPITAL MANAGEMENT LP trimmed | 1,066,239 | $3M | 1.1% | 2026-Q1 |
| Ikarian Capital, LLC | 900,000 | $2M | 0.9% | 2026-Q1 |
| GOLDMAN SACHS GROUP INC added | 783,220 | $2M | 0.8% | 2026-Q1 |
| CANTOR FITZGERALD, L. P. added | 765,000 | $2M | 0.8% | 2026-Q1 |
| DIMENSIONAL FUND ADVISORS LP added | 740,648 | $2M | 0.8% | 2026-Q1 |
| Burkehill Global Management, LP | 700,000 | $2M | 0.7% | 2026-Q1 |
| SCHRODER INVESTMENT MANAGEMENT GROUP | 756,637 | $2M | 0.7% | 2026-Q1 |
| UBS Group AG added | 606,664 | $2M | 0.6% | 2026-Q1 |
| VANGUARD FIDUCIARY TRUST CO new | 570,191 | $2M | 0.6% | 2026-Q1 |
| GSA CAPITAL PARTNERS LLP added | 561,726 | $2M | 0.6% | 2026-Q1 |
| KVP Capital Advisors, LP | 505,431 | $1M | 0.5% | 2026-Q1 |
| STATE STREET CORP added | 469,978 | $1M | 0.5% | 2026-Q1 |
| PRICE T ROWE ASSOCIATES INC /MD/ trimmed | 442,277 | $1M | 0.5% | 2026-Q1 |
| Raiffeisen Bank International AG | 450,000 | $1M | 0.4% | 2026-Q1 |
| Almitas Capital LLC trimmed | 337,391 | $908K | 0.4% | 2026-Q1 |
| BANK OF AMERICA CORP /DE/ added | 269,257 | $724K | 0.3% | 2026-Q1 |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC added | 267,372 | $719K | 0.3% | 2026-Q1 |
| Diametric Capital, LP added | 262,831 | $707K | 0.3% | 2026-Q1 |
| JANE STREET GROUP, LLC trimmed | 248,594 | $669K | 0.3% | 2026-Q1 |
| WELLINGTON MANAGEMENT GROUP LLP added | 247,659 | $666K | 0.3% | 2026-Q1 |
| Point72 Asset Management, L.P. added | 246,615 | $663K | 0.3% | 2026-Q1 |
| BOOTHBAY FUND MANAGEMENT, LLC | 243,445 | $655K | 0.3% | 2026-Q1 |
| NORTHERN TRUST CORP | 238,442 | $641K | 0.2% | 2026-Q1 |
| 683 Capital Management, LLC trimmed | 225,000 | $605K | 0.2% | 2026-Q1 |
| Invesco Ltd. added | 192,383 | $518K | 0.2% | 2026-Q1 |
| D. E. Shaw & Co., Inc. added | 166,149 | $447K | 0.2% | 2026-Q1 |
| Hudson Bay Capital Management LP added | 161,726 | $435K | 0.2% | 2026-Q1 |
| Brevan Howard Capital Management LP new | 149,721 | $403K | 0.2% | 2026-Q1 |
| Squarepoint Ops LLC trimmed | 144,681 | $389K | 0.2% | 2026-Q1 |
| AMERICAN CENTURY COMPANIES INC added | 108,319 | $291K | 0.1% | 2026-Q1 |
| ExodusPoint Capital Management, LP added | 105,985 | $285K | 0.1% | 2026-Q1 |
| Graham Capital Management, L.P. trimmed | 101,688 | $274K | 0.1% | 2026-Q1 |
| HRT FINANCIAL LP trimmed | 98,500 | $264K | 0.1% | 2026-Q1 |
| BARCLAYS PLC trimmed | 97,792 | $263K | 0.1% | 2026-Q1 |
| NOMURA HOLDINGS INC added | 95,512 | $257K | 0.1% | 2026-Q1 |
| LETKO, BROSSEAU & ASSOCIATES INC | 90,475 | $243K | 0.1% | 2026-Q1 |
| Quadrature Capital Ltd added | 87,060 | $234K | 0.1% | 2026-Q1 |
| LPL Financial LLC added | 69,575 | $187K | 0.1% | 2026-Q1 |
| TD Asset Management Inc trimmed | 66,924 | $180K | 0.1% | 2026-Q1 |
| MATAURO, LLC | 55,108 | $148K | 0.1% | 2026-Q1 |
| Bank of New York Mellon Corp added | 54,299 | $146K | 0.1% | 2026-Q1 |
| OMERS ADMINISTRATION Corp trimmed | 54,100 | $146K | 0.1% | 2026-Q1 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 50,824 | $137K | 0.1% | 2026-Q1 |
| Stonepine Capital Management, LLC trimmed | 50,000 | $134K | 0.1% | 2026-Q1 |
| PRELUDE CAPITAL MANAGEMENT, LLC added | 43,416 | $117K | 0.0% | 2026-Q1 |
| Virtu Financial LLC added | 38,703 | $104K | 0.0% | 2026-Q1 |
| Vanguard Global Advisers, LLC new | 35,751 | $96K | 0.0% | 2026-Q1 |
| Jefferies Financial Group Inc. trimmed | 33,442 | $90K | 0.0% | 2026-Q1 |
| AXQ CAPITAL, LP new | 28,938 | $78K | 0.0% | 2026-Q1 |
| Schonfeld Strategic Advisors LLC trimmed | 28,172 | $76K | 0.0% | 2026-Q1 |
| CITIGROUP INC trimmed | 27,473 | $74K | 0.0% | 2026-Q1 |
| MERCER GLOBAL ADVISORS INC /ADV | 26,510 | $71K | 0.0% | 2026-Q1 |
| FRED ALGER MANAGEMENT, LLC trimmed | 23,157 | $62K | 0.0% | 2026-Q1 |
| Catalyst Funds Management Pty Ltd added | 21,300 | $57K | 0.0% | 2026-Q1 |
| Grey Ledge Advisors, LLC new | 20,000 | $54K | 0.0% | 2026-Q1 |
| RAYMOND JAMES FINANCIAL INC new | 19,769 | $53K | 0.0% | 2026-Q1 |
| Clear Harbor Asset Management, LLC | 19,500 | $52K | 0.0% | 2026-Q1 |
| VANGUARD GROUP INC added | 4,419,458 | $10M | 3.8% | 2025-Q4 stale |
| HEIGHTS CAPITAL MANAGEMENT, INC trimmed | 2,084,202 | $5M | 1.9% | 2025-Q3 stale |
| Alyeska Investment Group, L.P. trimmed | 1,300,000 | $3M | 1.2% | 2025-Q3 stale |
| Anson Funds Management LP new | 1,822,830 | $3M | 1.1% | 2025-Q2 stale |
| Blue Owl Capital Holdings LP new | 1,125,000 | $2M | 0.7% | 2025-Q2 stale |
| TWO SIGMA ADVISERS, LP added | 737,900 | $2M | 0.6% | 2025-Q4 stale |
| Ensign Peak Advisors, Inc added | 550,000 | $1M | 0.5% | 2025-Q4 stale |
| Integral Health Asset Management, LLC added | 850,000 | $1M | 0.5% | 2025-Q1 stale |
| Nuveen, LLC new | 434,389 | $602K | 0.2% | 2025-Q1 stale |
| ACADIAN ASSET MANAGEMENT LLC added | 186,521 | $433K | 0.2% | 2025-Q3 stale |
| PRUDENTIAL FINANCIAL INC trimmed | 284,000 | $432K | 0.2% | 2025-Q2 stale |
| AXA S.A. added | 270,516 | $411K | 0.2% | 2025-Q2 stale |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP trimmed | 138,281 | $303K | 0.1% | 2025-Q4 stale |
| FEDERATED HERMES, INC. trimmed | 112,028 | $262K | 0.1% | 2025-Q3 stale |
| Atle Fund Management AB trimmed | 182,354 | $253K | 0.1% | 2025-Q1 stale |
| Thrivent Financial for Lutherans | 95,327 | $145K | 0.1% | 2025-Q2 stale |
| TCG Crossover Management, LLC | 86,795 | $132K | 0.1% | 2025-Q2 stale |
| ALLIANCEBERNSTEIN L.P. | 64,630 | $90K | 0.0% | 2025-Q1 stale |
| Cubist Systematic Strategies, LLC trimmed | 37,744 | $88K | 0.0% | 2025-Q3 stale |
| Jain Global LLC new | 56,160 | $85K | 0.0% | 2025-Q2 stale |
| Lighthouse Investment Partners, LLC new | 38,880 | $85K | 0.0% | 2025-Q4 stale |
| RHUMBLINE ADVISERS trimmed | 61,388 | $85K | 0.0% | 2025-Q1 stale |
| CITADEL ADVISORS LLC trimmed | 33,502 | $73K | 0.0% | 2025-Q4 stale |
| STIFEL FINANCIAL CORP added | 49,554 | $69K | 0.0% | 2025-Q1 stale |
| SG Americas Securities, LLC added | 30,629 | $67K | 0.0% | 2025-Q4 stale |
| MYDA Advisors LLC trimmed | 40,000 | $61K | 0.0% | 2025-Q2 stale |
| COMERICA BANK added | 41,599 | $58K | 0.0% | 2025-Q1 stale |
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.