Who owns Arcellx (ACLX)
Which tracked institutional funds hold ACLX, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See ACLX company fundamentals →
Ownership as of the 2026-Q1 13F filings (latest filed 2026-08-14). 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.
Conviction spread
ACLX’s largest tracked holder by dollar value, GILEAD SCIENCES, INC., sizes it at 46.8% of its own reported 13F book, while the median holder sizes it at 0.2% of theirs — a 46.6pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in ACLX 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, we do not read how tracked institutions changed their ACLX positions: many holders could not be matched across the two filings, most often because the security’s identifier changed and our mapping is incomplete, or because funds are still filing for the newer quarter. 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
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 |
|---|---|---|---|---|
| GILEAD SCIENCES, INC. | 6,720,803 | $772M | 10.6% | 2026-Q1 |
| Paradigm Biocapital Advisors LP added | 5,774,016 | $663M | 9.1% | 2026-Q1 |
| NEA Management Company, LLC | 3,045,262 | $350M | 4.8% | 2026-Q1 |
| BlackRock, Inc. trimmed | 2,998,176 | $344M | 4.7% | 2026-Q1 |
| Pentwater Capital Management LP new | 2,870,000 | $330M | 4.5% | 2026-Q1 |
| VANGUARD CAPITAL MANAGEMENT LLC new | 2,425,218 | $278M | 3.8% | 2026-Q1 |
| VANGUARD PORTFOLIO MANAGEMENT LLC new | 2,424,818 | $278M | 3.8% | 2026-Q1 |
| SR One Capital Management, LP | 2,346,630 | $269M | 3.7% | 2026-Q1 |
| FIL Ltd new | 2,339,192 | $269M | 3.7% | 2026-Q1 |
| HBK INVESTMENTS L P new | 2,278,517 | $262M | 3.6% | 2026-Q1 |
| T. Rowe Price Investment Management, Inc. trimmed | 2,255,878 | $259M | 3.6% | 2026-Q1 |
| STATE STREET CORP trimmed | 1,675,895 | $192M | 2.6% | 2026-Q1 |
| GLAZER CAPITAL, LLC new | 1,507,128 | $173M | 2.4% | 2026-Q1 |
| GOLDMAN SACHS GROUP INC added | 1,312,155 | $151M | 2.1% | 2026-Q1 |
| GEODE CAPITAL MANAGEMENT, LLC added | 1,028,666 | $118M | 1.6% | 2026-Q1 |
| MORGAN STANLEY added | 925,813 | $106M | 1.5% | 2026-Q1 |
| JPMORGAN CHASE & CO trimmed | 593,573 | $68M | 0.9% | 2026-Q1 |
| Davidson Kempner Capital Management LP new | 559,644 | $64M | 0.9% | 2026-Q1 |
| TIG Advisors, LLC new | 541,378 | $62M | 0.9% | 2026-Q1 |
| MILLENNIUM MANAGEMENT LLC added | 502,846 | $58M | 0.8% | 2026-Q1 |
| BALYASNY ASSET MANAGEMENT L.P. added | 479,763 | $55M | 0.8% | 2026-Q1 |
| TUDOR INVESTMENT CORP ET AL added | 462,588 | $53M | 0.7% | 2026-Q1 |
| BANK OF AMERICA CORP /DE/ added | 452,333 | $52M | 0.7% | 2026-Q1 |
| O'Connor Alternative Investments LLC new | 450,504 | $52M | 0.7% | 2026-Q1 |
| Magnetar Financial LLC new | 394,931 | $45M | 0.6% | 2026-Q1 |
| ALPINE ASSOCIATES MANAGEMENT INC. new | 378,000 | $43M | 0.6% | 2026-Q1 |
| NEXPOINT ASSET MANAGEMENT, L.P. new | 373,150 | $43M | 0.6% | 2026-Q1 |
| Affinity Asset Advisors, LLC trimmed | 362,764 | $42M | 0.6% | 2026-Q1 |
| NORTHERN TRUST CORP added | 350,065 | $40M | 0.6% | 2026-Q1 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC added | 346,092 | $40M | 0.5% | 2026-Q1 |
| ALLIANCEBERNSTEIN L.P. added | 544,227 | $35M | 0.5% | 2026-Q1 |
| VANGUARD FIDUCIARY TRUST CO new | 308,546 | $35M | 0.5% | 2026-Q1 |
| Qube Research & Technologies Ltd added | 303,847 | $35M | 0.5% | 2026-Q1 |
| First Trust Capital Management L.P. new | 238,235 | $27M | 0.4% | 2026-Q1 |
| AQR Arbitrage LLC new | 231,730 | $27M | 0.4% | 2026-Q1 |
| AJU IB Investment Co., Ltd. | 223,486 | $26M | 0.4% | 2026-Q1 |
| LMR Partners LLP new | 212,495 | $24M | 0.3% | 2026-Q1 |
| BARCLAYS PLC added | 207,642 | $24M | 0.3% | 2026-Q1 |
| SOROS FUND MANAGEMENT LLC new | 200,000 | $23M | 0.3% | 2026-Q1 |
| GABELLI FUNDS LLC new | 195,900 | $22M | 0.3% | 2026-Q1 |
| UBS Group AG trimmed | 194,709 | $22M | 0.3% | 2026-Q1 |
| Verition Fund Management LLC added | 187,354 | $22M | 0.3% | 2026-Q1 |
| WATER ISLAND CAPITAL LLC new | 183,409 | $21M | 0.3% | 2026-Q1 |
| Man Group plc added | 180,000 | $21M | 0.3% | 2026-Q1 |
| Rock Springs Capital Management LP | 169,859 | $20M | 0.3% | 2026-Q1 |
| GABELLI & Co INVESTMENT ADVISERS, INC. new | 152,400 | $17M | 0.2% | 2026-Q1 |
| BNP PARIBAS FINANCIAL MARKETS added | 151,558 | $17M | 0.2% | 2026-Q1 |
| Groupe la Francaise new | 151,046 | $17M | 0.2% | 2026-Q1 |
| Bank of New York Mellon Corp added | 143,099 | $16M | 0.2% | 2026-Q1 |
| CREDIT INDUSTRIEL ET COMMERCIAL new | 134,648 | $15M | 0.2% | 2026-Q1 |
| Woodline Partners LP trimmed | 123,750 | $14M | 0.2% | 2026-Q1 |
| GARDNER LEWIS ASSET MANAGEMENT L P new | 123,197 | $14M | 0.2% | 2026-Q1 |
| Hudson Bay Capital Management LP trimmed | 122,900 | $14M | 0.2% | 2026-Q1 |
| PICTON MAHONEY ASSET MANAGEMENT new | 120,000 | $14M | 0.2% | 2026-Q1 |
| FMR LLC trimmed | 119,309 | $14M | 0.2% | 2026-Q1 |
| Slotnik Capital, LLC new | 118,000 | $14M | 0.2% | 2026-Q1 |
| ODDO BHF ASSET MANAGEMENT SAS new | 115,000 | $13M | 0.2% | 2026-Q1 |
| PRELUDE CAPITAL MANAGEMENT, LLC new | 98,849 | $11M | 0.2% | 2026-Q1 |
| RENAISSANCE TECHNOLOGIES LLC added | 96,400 | $11M | 0.2% | 2026-Q1 |
| JANUS HENDERSON GROUP PLC trimmed | 90,280 | $10M | 0.1% | 2026-Q1 |
| CIBRA Capital Ltd new | 88,623 | $10M | 0.1% | 2026-Q1 |
| Nuveen, LLC added | 85,294 | $10M | 0.1% | 2026-Q1 |
| DEUTSCHE BANK AG\ trimmed | 80,664 | $9M | 0.1% | 2026-Q1 |
| Cinctive Capital Management LP added | 80,000 | $9M | 0.1% | 2026-Q1 |
| Chicago Capital Management, LLC new | 92,951 | $8M | 0.1% | 2026-Q1 |
| Sagefield Capital LP new | 65,097 | $7M | 0.1% | 2026-Q1 |
| Athos Capital Ltd new | 64,900 | $7M | 0.1% | 2026-Q1 |
| Russell Investments Group, Ltd. trimmed | 61,905 | $7M | 0.1% | 2026-Q1 |
| SAMSARA BIOCAPITAL, LLC | 60,873 | $7M | 0.1% | 2026-Q1 |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC trimmed | 57,289 | $7M | 0.1% | 2026-Q1 |
| Voleon Capital Management LP new | 56,720 | $7M | 0.1% | 2026-Q1 |
| IFP Advisors, Inc added | 13 | $1K | 0.0% | 2026-Q2 (1 quarter ahead of as-of) |
| Strengthening Families & Communities, LLC | 500 | — | 0.0% | 2026-Q2 (1 quarter ahead of as-of) |
| GAMMA Investing LLC added | 460 | — | 0.0% | 2026-Q2 (1 quarter ahead of as-of) |
| Gleason Group, Inc. new | 3 | — | 0.0% | 2026-Q2 (1 quarter ahead of as-of) |
| CONGRESS ASSET MANAGEMENT CO added | 47,651 | — | 0.0% | 2026-Q2 (1 quarter ahead of as-of) |
| VANGUARD GROUP INC added | 4,081,519 | $266M | 3.7% | 2025-Q4 stale (1 quarter behind) |
| Vestal Point Capital, LP added | 2,925,000 | $191M | 2.6% | 2025-Q4 stale (1 quarter behind) |
| PERCEPTIVE ADVISORS LLC trimmed | 1,466,071 | $96M | 1.3% | 2025-Q4 stale (1 quarter behind) |
| RA CAPITAL MANAGEMENT, L.P. trimmed | 1,267,156 | $83M | 1.1% | 2025-Q4 stale (1 quarter behind) |
| BAMCO INC /NY/ added | 609,697 | $40M | 0.5% | 2025-Q4 stale (1 quarter behind) |
| LORD, ABBETT & CO. LLC added | 449,634 | $29M | 0.4% | 2025-Q4 stale (1 quarter behind) |
| AMERICAN CENTURY COMPANIES INC added | 419,080 | $27M | 0.4% | 2025-Q4 stale (1 quarter behind) |
| Hood River Capital Management LLC new | 335,500 | $22M | 0.3% | 2025-Q4 stale (1 quarter behind) |
| STEMPOINT CAPITAL LP added | 332,860 | $22M | 0.3% | 2025-Q4 stale (1 quarter behind) |
| Fisher Asset Management, LLC new | 322,855 | $21M | 0.3% | 2025-Q4 stale (1 quarter behind) |
| TD Asset Management Inc added | 300,856 | $20M | 0.3% | 2025-Q4 stale (1 quarter behind) |
| WELLINGTON MANAGEMENT GROUP LLP trimmed | 214,776 | $14M | 0.2% | 2025-Q4 stale (1 quarter behind) |
| Integral Health Asset Management, LLC added | 200,000 | $13M | 0.2% | 2025-Q4 stale (1 quarter behind) |
| Catalio Capital Management, LP new | 156,109 | $10M | 0.1% | 2025-Q4 stale (1 quarter behind) |
| Rhenman & Partners Asset Management AB added | 133,500 | $9M | 0.1% | 2025-Q4 stale (1 quarter behind) |
| CLOUGH CAPITAL PARTNERS L P new | 129,780 | $8M | 0.1% | 2025-Q4 stale (1 quarter behind) |
| Parkman Healthcare Partners LLC trimmed | 128,111 | $8M | 0.1% | 2025-Q4 stale (1 quarter behind) |
| RAYMOND JAMES FINANCIAL INC trimmed | 122,346 | $8M | 0.1% | 2025-Q4 stale (1 quarter behind) |
| Logos Global Management LP trimmed | 115,000 | $7M | 0.1% | 2025-Q4 stale (1 quarter behind) |
| Capital World Investors | 783,011 | $64M | 0.9% | 2025-Q3 stale (2 quarters behind) |
| Cormorant Asset Management, LP trimmed | 775,000 | $64M | 0.9% | 2025-Q3 stale (2 quarters behind) |
| First Turn Management, LLC added | 313,733 | $26M | 0.4% | 2025-Q3 stale (2 quarters behind) |
| BAKER BROS. ADVISORS LP | 166,825 | $14M | 0.2% | 2025-Q3 stale (2 quarters behind) |
| GREAT POINT PARTNERS LLC added | 100,000 | $7M | 0.1% | 2025-Q2 stale (3 quarters behind) |
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.