Who owns MLYS (MLYS)
Which tracked institutional funds hold MLYS, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See MLYS company fundamentals →
Ownership as of the 2026-Q1 13F filings. 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
43 tracked funds added or opened MLYS while 107 trimmed or exited it between 2025-Q4 and 2026-Q1 — 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
MLYS’s largest tracked holder by dollar value, Catalys Pacific, LLC, sizes it at 92.8% of its own reported 13F book, while the median holder sizes it at 0.1% of theirs — a 92.7pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in MLYS 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 215 tracked filers holding MLYS, 130 increased or opened the position and 94 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 MLYS 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 12
- VANGUARD CAPITAL MANAGEMENT LLC$66M
- VANGUARD PORTFOLIO MANAGEMENT LLC$19M
- Troluce Capital Advisors LLC$18M
- Capital World Investors$11M
- VANGUARD FIDUCIARY TRUST CO$10M
- MARK ASSET MANAGEMENT LP$4M
Full exits 22
- VANGUARD GROUP INC$106M
- Holocene Advisors, LP$58M
- SAMLYN CAPITAL, LLC$47M
- Capital International Investors$42M
- FARALLON CAPITAL MANAGEMENT LLC$30M
- Siren, L.L.C.$25M
Largest adds
- WELLINGTON MANAGEMENT GROUP LLP$60M
- Nantahala Capital Management, LLC$20M
- ORBIMED ADVISORS LLC$20M
- SPHERA FUNDS MANAGEMENT LTD.$20M
- MILLENNIUM MANAGEMENT LLC$11M
- Pale Fire Capital SE$10M
Largest trims
- Catalys Pacific, LLC$73M
- RA CAPITAL MANAGEMENT, L.P.$57M
- FMR LLC$54M
- SAMSARA BIOCAPITAL, LLC$54M
- JANUS HENDERSON GROUP PLC$43M
- STATE STREET CORP$36M
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 |
|---|---|---|---|---|
| Catalys Pacific, LLC | 7,903,838 | $214M | 7.6% | 2026-Q1 |
| RA CAPITAL MANAGEMENT, L.P. added | 7,692,750 | $208M | 7.4% | 2026-Q1 |
| SAMSARA BIOCAPITAL, LLC | 5,871,018 | $159M | 5.7% | 2026-Q1 |
| FMR LLC trimmed | 4,771,089 | $129M | 4.6% | 2026-Q1 |
| BlackRock, Inc. added | 4,481,582 | $121M | 4.3% | 2026-Q1 |
| WELLINGTON MANAGEMENT GROUP LLP added | 3,271,548 | $89M | 3.2% | 2026-Q1 |
| STATE STREET CORP trimmed | 2,935,940 | $80M | 2.8% | 2026-Q1 |
| Caligan Partners LP | 2,772,654 | $75M | 2.7% | 2026-Q1 |
| VANGUARD CAPITAL MANAGEMENT LLC new | 2,454,363 | $66M | 2.4% | 2026-Q1 |
| Laurion Capital Management LP added | 2,232,040 | $60M | 2.2% | 2026-Q1 |
| ORBIMED ADVISORS LLC added | 2,052,900 | $56M | 2.0% | 2026-Q1 |
| Point72 Asset Management, L.P. added | 1,911,433 | $52M | 1.8% | 2026-Q1 |
| FRANKLIN RESOURCES INC trimmed | 1,784,662 | $48M | 1.7% | 2026-Q1 |
| ANDERA PARTNERS | 1,591,917 | $43M | 1.5% | 2026-Q1 |
| SR One Capital Management, LP | 1,563,966 | $42M | 1.5% | 2026-Q1 |
| SUVRETTA CAPITAL MANAGEMENT, LLC | 1,538,662 | $42M | 1.5% | 2026-Q1 |
| Polar Capital Holdings Plc added | 1,500,749 | $41M | 1.5% | 2026-Q1 |
| PRICE T ROWE ASSOCIATES INC /MD/ added | 1,343,313 | $36M | 1.3% | 2026-Q1 |
| SPHERA FUNDS MANAGEMENT LTD. added | 1,339,971 | $36M | 1.3% | 2026-Q1 |
| ALLIANCEBERNSTEIN L.P. added | 975,961 | $35M | 1.3% | 2026-Q1 |
| GEODE CAPITAL MANAGEMENT, LLC added | 1,301,135 | $35M | 1.3% | 2026-Q1 |
| JENNISON ASSOCIATES LLC added | 1,266,174 | $34M | 1.2% | 2026-Q1 |
| ARMISTICE CAPITAL, LLC added | 1,176,000 | $32M | 1.1% | 2026-Q1 |
| BANK OF AMERICA CORP /DE/ added | 1,100,372 | $30M | 1.1% | 2026-Q1 |
| Pictet Asset Management Holding SA added | 1,034,438 | $28M | 1.0% | 2026-Q1 |
| BOOTHBAY FUND MANAGEMENT, LLC added | 1,001,728 | $27M | 1.0% | 2026-Q1 |
| Qube Research & Technologies Ltd added | 914,728 | $25M | 0.9% | 2026-Q1 |
| Nantahala Capital Management, LLC added | 895,481 | $24M | 0.9% | 2026-Q1 |
| D. E. Shaw & Co., Inc. trimmed | 887,192 | $24M | 0.9% | 2026-Q1 |
| AMERICAN CENTURY COMPANIES INC trimmed | 884,107 | $24M | 0.9% | 2026-Q1 |
| MORGAN STANLEY added | 849,184 | $23M | 0.8% | 2026-Q1 |
| Candriam S.C.A. added | 801,904 | $22M | 0.8% | 2026-Q1 |
| GOLDMAN SACHS GROUP INC trimmed | 785,043 | $21M | 0.8% | 2026-Q1 |
| Affinity Asset Advisors, LLC added | 750,000 | $20M | 0.7% | 2026-Q1 |
| Integral Health Asset Management, LLC | 750,000 | $20M | 0.7% | 2026-Q1 |
| VANGUARD PORTFOLIO MANAGEMENT LLC new | 706,658 | $19M | 0.7% | 2026-Q1 |
| Troluce Capital Advisors LLC new | 655,000 | $18M | 0.6% | 2026-Q1 |
| CITADEL ADVISORS LLC added | 600,041 | $16M | 0.6% | 2026-Q1 |
| STEMPOINT CAPITAL LP added | 533,378 | $14M | 0.5% | 2026-Q1 |
| MILLENNIUM MANAGEMENT LLC added | 525,260 | $14M | 0.5% | 2026-Q1 |
| Davern Capital Partners, LP added | 447,153 | $12M | 0.4% | 2026-Q1 |
| 22NW, LP added | 444,325 | $12M | 0.4% | 2026-Q1 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC trimmed | 443,898 | $12M | 0.4% | 2026-Q1 |
| NORTHERN TRUST CORP added | 442,874 | $12M | 0.4% | 2026-Q1 |
| Rock Springs Capital Management LP added | 439,751 | $12M | 0.4% | 2026-Q1 |
| Catalio Capital Management, LP added | 439,041 | $12M | 0.4% | 2026-Q1 |
| Capital World Investors new | 398,179 | $11M | 0.4% | 2026-Q1 |
| RENAISSANCE TECHNOLOGIES LLC added | 382,800 | $10M | 0.4% | 2026-Q1 |
| Parkman Healthcare Partners LLC trimmed | 380,137 | $10M | 0.4% | 2026-Q1 |
| VANGUARD FIDUCIARY TRUST CO new | 375,262 | $10M | 0.4% | 2026-Q1 |
| Pale Fire Capital SE added | 365,626 | $10M | 0.4% | 2026-Q1 |
| TimesSquare Capital Management, LLC trimmed | 338,798 | $9M | 0.3% | 2026-Q1 |
| TWO SIGMA INVESTMENTS, LP trimmed | 311,488 | $8M | 0.3% | 2026-Q1 |
| LORD, ABBETT & CO. LLC trimmed | 300,913 | $8M | 0.3% | 2026-Q1 |
| Rhenman & Partners Asset Management AB added | 263,071 | $7M | 0.3% | 2026-Q1 |
| ALGERT GLOBAL LLC added | 260,264 | $7M | 0.3% | 2026-Q1 |
| SG Americas Securities, LLC trimmed | 225,833 | $6M | 0.2% | 2026-Q1 |
| AMERIPRISE FINANCIAL INC added | 221,305 | $6M | 0.2% | 2026-Q1 |
| VOYA INVESTMENT MANAGEMENT LLC added | 216,089 | $6M | 0.2% | 2026-Q1 |
| Russell Investments Group, Ltd. added | 203,504 | $6M | 0.2% | 2026-Q1 |
| FINDELL CAPITAL MANAGEMENT LLC added | 202,000 | $5M | 0.2% | 2026-Q1 |
| Schonfeld Strategic Advisors LLC added | 177,585 | $5M | 0.2% | 2026-Q1 |
| Buckley Capital Advisors, LLC trimmed | 173,100 | $5M | 0.2% | 2026-Q1 |
| TUDOR INVESTMENT CORP ET AL added | 155,740 | $4M | 0.2% | 2026-Q1 |
| ADAR1 Capital Management, LLC added | 154,686 | $4M | 0.1% | 2026-Q1 |
| Burkehill Global Management, LP | 150,000 | $4M | 0.1% | 2026-Q1 |
| AQR CAPITAL MANAGEMENT LLC added | 148,082 | $4M | 0.1% | 2026-Q1 |
| MARK ASSET MANAGEMENT LP added | 144,875 | $4M | 0.1% | 2026-Q1 |
| PFM Health Sciences, LP added | 142,677 | $4M | 0.1% | 2026-Q1 |
| Artia Global Partners LP | 137,800 | $4M | 0.1% | 2026-Q1 |
| DIMENSIONAL FUND ADVISORS LP trimmed | 137,433 | $4M | 0.1% | 2026-Q1 |
| Y-Intercept (Hong Kong) Ltd added | 132,099 | $4M | 0.1% | 2026-Q1 |
| Bank of New York Mellon Corp trimmed | 129,964 | $4M | 0.1% | 2026-Q1 |
| Swedbank AB trimmed | 122,100 | $3M | 0.1% | 2026-Q1 |
| SCHRODER INVESTMENT MANAGEMENT GROUP | 130,592 | $3M | 0.1% | 2026-Q1 |
| Ensign Peak Advisors, Inc | 112,190 | $3M | 0.1% | 2026-Q1 |
| Nuveen, LLC trimmed | 112,007 | $3M | 0.1% | 2026-Q1 |
| Squarepoint Ops LLC trimmed | 105,491 | $3M | 0.1% | 2026-Q1 |
| Nationale-Nederlanden Powszechne Towarzystwo Emerytalne S.A. trimmed | 104,961 | $3M | 0.1% | 2026-Q1 |
| CAPITAL FUND MANAGEMENT S.A. new | 102,202 | $3M | 0.1% | 2026-Q1 |
| UBS Group AG trimmed | 98,029 | $3M | 0.1% | 2026-Q1 |
| VANGUARD GROUP INC trimmed | 2,916,730 | $106M | 3.8% | 2025-Q4 stale |
| Holocene Advisors, LP added | 1,602,035 | $58M | 2.1% | 2025-Q4 stale |
| SAMLYN CAPITAL, LLC new | 1,304,932 | $47M | 1.7% | 2025-Q4 stale |
| Capital International Investors trimmed | 1,163,290 | $42M | 1.5% | 2025-Q4 stale |
| TCG Crossover Management, LLC | 2,470,265 | $39M | 1.4% | 2025-Q1 stale |
| FARALLON CAPITAL MANAGEMENT LLC trimmed | 823,296 | $30M | 1.1% | 2025-Q4 stale |
| Siren, L.L.C. new | 699,999 | $25M | 0.9% | 2025-Q4 stale |
| Nearwater Capital Markets, Ltd new | 450,000 | $17M | 0.6% | 2025-Q3 stale |
| TWO SIGMA ADVISERS, LP new | 353,700 | $13M | 0.5% | 2025-Q4 stale |
| Iron Triangle Partners LP new | 257,085 | $9M | 0.3% | 2025-Q4 stale |
| TANG CAPITAL MANAGEMENT LLC | 200,000 | $8M | 0.3% | 2025-Q3 stale |
| Ikarian Capital, LLC trimmed | 200,000 | $7M | 0.3% | 2025-Q4 stale |
| Atika Capital Management LLC new | 174,000 | $7M | 0.2% | 2025-Q3 stale |
| Jain Global LLC added | 120,854 | $5M | 0.2% | 2025-Q3 stale |
| Simplify Asset Management Inc. trimmed | 114,182 | $4M | 0.1% | 2025-Q4 stale |
| ADAGE CAPITAL PARTNERS GP, L.L.C. new | 105,000 | $4M | 0.1% | 2025-Q3 stale |
| Informed Momentum Co LLC trimmed | 96,135 | $3M | 0.1% | 2025-Q4 stale |
| SILVERARC CAPITAL MANAGEMENT, LLC added | 94,983 | $3M | 0.1% | 2025-Q4 stale |
| Hudson Bay Capital Management LP | 75,768 | $3M | 0.1% | 2025-Q4 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.