Boundless Bio, Inc.
BOLD- Exchange
- Nasdaq
- Industry
- Pharmaceutical Preparations
- SEC CIK
- 0001782303
In the last 90 days, Boundless Bio, Inc. insiders filed 5 open-market purchases and 1 sale; 40 institutions reported holding it in 13F filings for Q2 2026, worth $38.3M in total; no superinvestor holds it.
Holders of 5% or more of BOLD
Holders whose latest Schedule 13D or 13G filing reports 5% or more of Boundless Bio, Inc., largest stake first. The change is against the holder's previous filing.
| Holder | Latest form | Stake | Change | First filed | Latest filing | Filing |
|---|---|---|---|---|---|---|
| FMR LLC | 13G/A | 12.00%2.68M shares | – | Apr 10, 20242 filings | Feb 5, 2026 | SEC |
| Tang Capital Management LLC | 13G | 11.30%2.53M shares | New | Jun 29, 20261 filing | Jun 29, 2026 | SEC |
| Hornby Zachary | 13G | 9.80%2.43M shares | New | Aug 27, 20261 filing | Aug 27, 2026 | SEC |
| ADAR1 Capital Management, LLC | 13G | 8.80%1.97M shares | New | Aug 14, 20261 filing | Aug 14, 2026 | SEC |
Stakes are as of each holder's latest filing. Holders whose last filing was in the old format (before December 18, 2024) have no stake on record and are not listed, and after an acquisition or delisting holders usually stop filing.
13D and 13G filings
13 Schedule 13D and 13G filings on Boundless Bio, Inc., newest first, including old-format filings without a stake.
| Filed (ET) | Filer | Form | Stake | Change | Event date | Filing |
|---|---|---|---|---|---|---|
| Aug 27, 20269:05 PM ET | Hornby Zachary | 13G | 9.80%2.43M shares | New | Oct 14, 2025 | SEC |
| Aug 14, 20269:28 PM ET | ADAR1 Capital Management, LLCand 1 other | 13G | 8.80%1.97M shares | New | Jun 30, 2026 | SEC |
| Aug 14, 20264:01 PM ET | Citadel Advisors LLCand 6 others | 13G/A | 0.60%145.1K shares | −5.80 ppfrom 6.40%Below 5% | Jun 30, 2026 | SEC |
| Jun 29, 20267:58 PM ET | Tang Capital Management LLCand 5 others | 13G | 11.30%2.53M shares | New | Jun 23, 2026 | SEC |
| Feb 17, 20266:47 PM ET | Nextech VI GP S.A.R.L.and 4 others | 13G/A | 0.00%0 shares | –Below 5% | Dec 31, 2025 | SEC |
| Feb 5, 20261:16 PM ET | FMR LLCand 1 other | 13G/A | 12.00%2.68M shares | – | Dec 31, 2025 | SEC |
| Dec 4, 20256:35 PM ET | Citadel Advisors LLCand 6 others | 13G | 6.40%1.43M shares | New | Nov 26, 2025 | SEC |
| Aug 14, 20255:57 PM ET | Ra Capital Management, L.P.and 3 others | 13G/A | 0.00%0 shares | –Below 5% | Jun 30, 2025 | SEC |
| Oct 29, 2024 | ARCH Venture Fund IX, L.P. | 13DOld format | – | New | – | SEC |
| Apr 12, 2024 | Ra Capital Management, L.P. | 13GOld format | – | New | – | SEC |
| Apr 12, 2024 | Nextech VI GP S.A.R.L. | 13GOld format | – | New | – | SEC |
| Apr 10, 2024 | FMR LLC | 13GOld format | – | New | – | SEC |
| Apr 9, 2024 | Bayer Healthcare LLC | 13GOld format | – | New | – | SEC |
Form 144: proposed insider sales
Notices from officers, directors and other affiliates planning to sell Boundless Bio, Inc. shares.
No Form 144 notices for Boundless Bio, Inc. are on file.