Who owns BillionToOne (BLLN)
Which tracked institutional funds hold BLLN, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See BLLN 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
The tracked-fund tape on BLLN is one-sided between 2026-Q1 and 2026-Q2: 85 added or opened and 14 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
BLLN’s largest tracked holder by dollar value, ADAMS STREET PARTNERS LLC, sizes it at 46.4% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 46.4pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in BLLN 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 148 tracked filers holding BLLN, 119 increased or opened the position and 25 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 BLLN 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 34
- MILLENNIUM MANAGEMENT LLC$51M
- FULLER & THALER ASSET MANAGEMENT, INC.$50M
- OBERWEIS ASSET MANAGEMENT INC/$36M
- VOLORIDGE INVESTMENT MANAGEMENT, LLC$14M
- FRED ALGER MANAGEMENT, LLC$14M
- HEALTHCARE OF ONTARIO PENSION PLAN TRUST FUND$10M
Full exits 10
- NVP ASSOCIATES, LLC$41M
- Capital International Investors$14M
- PFM Health Sciences, LP$7M
- Deep Track Capital, LP$4M
- LORD, ABBETT & CO. LLC$3M
- PUBLIC EMPLOYEES RETIREMENT SYSTEM OF OHIO$2M
Largest adds
- VANGUARD PORTFOLIO MANAGEMENT LLC$89M
- VANGUARD CAPITAL MANAGEMENT LLC$82M
- ADAMS STREET PARTNERS LLC$70M
- Invesco Ltd.$68M
- PRICE T ROWE ASSOCIATES INC /MD/$63M
- NEUBERGER BERMAN GROUP LLC$54M
Largest trims
- Civilization Ventures Management, LLC$87M
- MASSACHUSETTS FINANCIAL SERVICES CO /MA/$3M
- TWO SIGMA INVESTMENTS, LP$3M
- Squarepoint Ops LLC$759K
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.
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.