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Institutional Ownership · SEC Form 13F

Who owns ASMB (ASMB)


Which tracked institutional funds hold ASMB, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See ASMB 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.

75
Institutional holders
13,568,764
Shares held (tracked funds)
85.6%
Of shares outstanding

How the tape is positioned

12 tracked funds added or opened ASMB while 31 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

ASMB’s largest tracked holder by dollar value, GILEAD SCIENCES, INC., sizes it at 5.9% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 5.9pp conviction gap — its largest holder concentrates the name more heavily than the typical one.

Book-share is each fund’s reported value in ASMB 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 75 tracked filers holding ASMB, 47 increased or opened the position and 28 reduced or closed it; over the same quarter, open-market insider Form 4 buying and selling roughly offset.

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 ASMB 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 6

  • VANGUARD CAPITAL MANAGEMENT LLC$14M
  • HighVista Strategies LLC$2M
  • VANGUARD FIDUCIARY TRUST CO$2M
  • WELLINGTON MANAGEMENT GROUP LLP$735K
  • Squarepoint Ops LLC$661K
  • TWO SIGMA INVESTMENTS, LP$570K

Full exits 6

  • VANGUARD GROUP INC$19M
  • FRANKLIN RESOURCES INC$7M
  • SUPERSTRING CAPITAL MANAGEMENT LP$2M
  • Informed Momentum Co LLC$1M
  • Ellsworth Advisors, LLC$889K
  • SEI INVESTMENTS CO$604K

Largest adds

  • MILLENNIUM MANAGEMENT LLC$3M
  • Parkman Healthcare Partners LLC$3M
  • Schonfeld Strategic Advisors LLC$1M
  • Seven Fleet Capital Management LP$1M
  • GSA CAPITAL PARTNERS LLP$818K
  • Qube Research & Technologies Ltd$487K

Largest trims

  • GILEAD SCIENCES, INC.$28M
  • Point72 Asset Management, L.P.$11M
  • FARALLON CAPITAL MANAGEMENT LLC$8M
  • RA CAPITAL MANAGEMENT, L.P.$6M
  • Commodore Capital LP$6M
  • JANUS HENDERSON GROUP PLC$5M

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).

FundSharesReported value% of valueQuarter
GILEAD SCIENCES, INC.4,505,391$125M29.5%2026-Q1
FARALLON CAPITAL MANAGEMENT LLC1,227,590$34M8.0%2026-Q1
RA CAPITAL MANAGEMENT, L.P.1,020,410$28M6.7%2026-Q1
Commodore Capital LP1,000,000$28M6.5%2026-Q1
JANUS HENDERSON GROUP PLC added849,309$23M5.5%2026-Q1
Paradigm Biocapital Advisors LP665,251$18M4.4%2026-Q1
VANGUARD CAPITAL MANAGEMENT LLC new490,447$14M3.2%2026-Q1
Parkman Healthcare Partners LLC added411,227$11M2.7%2026-Q1
Point72 Asset Management, L.P. trimmed344,105$10M2.3%2026-Q1
Blackstone Inc. trimmed296,855$8M1.9%2026-Q1
MILLENNIUM MANAGEMENT LLC added233,650$6M1.5%2026-Q1
BlackRock, Inc. added202,743$6M1.3%2026-Q1
STEMPOINT CAPITAL LP added185,435$5M1.2%2026-Q1
B Group, Inc.175,706$5M1.1%2026-Q1
MARSHALL WACE, LLP added163,400$5M1.1%2026-Q1
ADAGE CAPITAL PARTNERS GP, L.L.C.161,000$4M1.1%2026-Q1
Patient Square Capital LP added136,315$4M0.9%2026-Q1
GEODE CAPITAL MANAGEMENT, LLC added132,971$4M0.9%2026-Q1
Schonfeld Strategic Advisors LLC added120,500$3M0.8%2026-Q1
Caption Management, LLC trimmed81,841$2M0.5%2026-Q1
HighVista Strategies LLC added74,735$2M0.5%2026-Q1
VANGUARD FIDUCIARY TRUST CO new71,606$2M0.5%2026-Q1
Qube Research & Technologies Ltd added69,256$2M0.5%2026-Q1
STATE STREET CORP added56,689$2M0.4%2026-Q1
Seven Fleet Capital Management LP added56,147$2M0.4%2026-Q1
JPMORGAN CHASE & CO added53,962$1M0.3%2026-Q1
MONIMUS CAPITAL MANAGEMENT, LP added48,390$1M0.3%2026-Q1
GSA CAPITAL PARTNERS LLP added45,049$1M0.3%2026-Q1
NORTHERN TRUST CORP trimmed41,014$1M0.3%2026-Q1
Eversept Partners, LP trimmed40,889$1M0.3%2026-Q1
ARROWSTREET CAPITAL, LIMITED PARTNERSHIP added39,446$1M0.3%2026-Q1
GOLDMAN SACHS GROUP INC added36,205$1M0.2%2026-Q1
JANE STREET GROUP, LLC trimmed34,499$957K0.2%2026-Q1
MORGAN STANLEY added33,055$917K0.2%2026-Q1
SUSQUEHANNA INTERNATIONAL GROUP, LLP trimmed32,949$914K0.2%2026-Q1
683 Capital Management, LLC27,863$773K0.2%2026-Q1
BARCLAYS PLC added27,050$751K0.2%2026-Q1
WELLINGTON MANAGEMENT GROUP LLP trimmed26,496$735K0.2%2026-Q1
CITADEL ADVISORS LLC trimmed25,437$706K0.2%2026-Q1
Squarepoint Ops LLC added23,804$661K0.2%2026-Q1
Trexquant Investment LP trimmed22,741$631K0.1%2026-Q1
Connor, Clark & Lunn Investment Management Ltd. added21,761$604K0.1%2026-Q1
TWO SIGMA INVESTMENTS, LP trimmed20,550$570K0.1%2026-Q1
ADAR1 Capital Management, LLC added19,947$554K0.1%2026-Q1
Palumbo Wealth Management LLC trimmed19,643$545K0.1%2026-Q1
FEDERATED HERMES, INC. trimmed18,904$525K0.1%2026-Q1
VANGUARD PORTFOLIO MANAGEMENT LLC new17,723$492K0.1%2026-Q1
Hudson Bay Capital Management LP added16,799$466K0.1%2026-Q1
RENAISSANCE TECHNOLOGIES LLC added15,651$434K0.1%2026-Q1
Susquehanna Portfolio Strategies, LLC added14,100$391K0.1%2026-Q1
EntryPoint Capital, LLC new12,384$344K0.1%2026-Q1
Brevan Howard Capital Management LP new11,112$308K0.1%2026-Q1
Jump Financial, LLC trimmed10,917$303K0.1%2026-Q1
BANK OF AMERICA CORP /DE/ added10,902$303K0.1%2026-Q1
XTX Topco Ltd trimmed10,785$299K0.1%2026-Q1
Engineers Gate Manager LP trimmed9,423$261K0.1%2026-Q1
AMERICAN CENTURY COMPANIES INC trimmed9,154$254K0.1%2026-Q1
CANADA PENSION PLAN INVESTMENT BOARD added8,500$236K0.1%2026-Q1
OMERS ADMINISTRATION Corp trimmed8,100$225K0.1%2026-Q1
Virtus Investment Advisers, LLC added7,553$210K0.0%2026-Q1
CITIGROUP INC added6,483$180K0.0%2026-Q1
Vanguard Global Advisers, LLC new4,615$128K0.0%2026-Q1
EverSource Wealth Advisors, LLC added200$23K0.0%2026-Q1
Tower Research Capital LLC (TRC) trimmed544$15K0.0%2026-Q1
UBS Group AG trimmed364$10K0.0%2026-Q1
NORTHWESTERN MUTUAL WEALTH MANAGEMENT CO trimmed260$7K0.0%2026-Q1
Aquatic Capital Management LLC new220$6K0.0%2026-Q1
RHUMBLINE ADVISERS190$5K0.0%2026-Q1
BNP PARIBAS FINANCIAL MARKETS added149$4K0.0%2026-Q1
Accent Capital Management, LLC new142$4K0.0%2026-Q1
OSAIC HOLDINGS, INC.100$3K0.0%2026-Q1
US BANCORP \DE\59$2K0.0%2026-Q1
FIFTH THIRD BANCORP new57$2K0.0%2026-Q1
Allworth Financial LP trimmed29$8050.0%2026-Q1
VANGUARD GROUP INC added572,898$19M4.6%2025-Q4 stale
Frazier Life Sciences Management, L.P. new456,249$12M2.8%2025-Q3 stale
FRANKLIN RESOURCES INC trimmed210,528$7M1.7%2025-Q4 stale
SUPERSTRING CAPITAL MANAGEMENT LP new65,273$2M0.5%2025-Q4 stale
MPM BIOIMPACT LLC new39,665$1M0.2%2025-Q3 stale
Informed Momentum Co LLC added29,523$1M0.2%2025-Q4 stale
Ellsworth Advisors, LLC trimmed29,735$889K0.2%2025-Q4 stale
Walleye Capital LLC trimmed24,501$627K0.1%2025-Q3 stale
SEI INVESTMENTS CO trimmed17,745$604K0.1%2025-Q4 stale
Quadrature Capital Ltd new17,935$459K0.1%2025-Q3 stale
RAYMOND JAMES FINANCIAL INC added13,082$445K0.1%2025-Q4 stale
ACADIAN ASSET MANAGEMENT LLC trimmed12,446$422K0.1%2025-Q4 stale
Cubist Systematic Strategies, LLC trimmed16,161$414K0.1%2025-Q3 stale
BRIDGEWAY CAPITAL MANAGEMENT, LLC15,225$390K0.1%2025-Q3 stale
Man Group plc trimmed13,227$240K0.1%2025-Q2 stale
ARMISTICE CAPITAL, LLC trimmed23,858$228K0.1%2025-Q1 stale
CHARLES SCHWAB INVESTMENT MANAGEMENT INC trimmed6,704$228K0.1%2025-Q4 stale
Lynx1 Capital Management LP new10,366$188K0.0%2025-Q2 stale
FMR LLC trimmed5,659$54K0.0%2025-Q1 stale
Farther Finance Advisors, LLC new154$5K0.0%2025-Q4 stale
WELLS FARGO & COMPANY/MN145$4K0.0%2025-Q3 stale
SBI Securities Co., Ltd. added68$2K0.0%2025-Q3 stale
AMERIFLEX GROUP, INC.83$1K0.0%2025-Q2 stale
QUADRANT CAPITAL GROUP LLC22$7490.0%2025-Q4 stale
Caitong International Asset Management Co., Ltd new34$6160.0%2025-Q2 stale
Point72 Europe (London) LLP new13$3320.0%2025-Q3 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.

HoldersTotal shares

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.

Learn how to read institutional ownership