BOLD · Insider Trading
Boundless Bio, Inc. Common Stock
Every open-market purchase and sale reported by BOLD officers, directors and 10%+ beneficial owners on SEC Form 4, which must be filed within two business days of the transaction. Sales often reflect scheduled 10b5-1 plans or tax withholding rather than a directional view, so read counts alongside the size and the filer.
| Filed | Insider | Role | Type | Shares | Value |
|---|---|---|---|---|---|
| 2026-10-20 | TANG CAPITAL MANAGEMENT LLC | 10%+ Owner | Buy | +298,948 | +$699.19K |
| 2026-08-28 | Kevin Tang | 10%+ Owner | Sell | −36,600 | −$108.70K |
| 2026-07-21 | TANG CAPITAL MANAGEMENT LLC | 10%+ Owner | Buy | +9,726 | +$23.73K |
| 2026-07-16 | TANG CAPITAL MANAGEMENT LLC | 10%+ Owner | Buy | +127,938 | +$311.29K |
| 2026-07-13 | TANG CAPITAL MANAGEMENT LLC | 10%+ Owner | Buy | +183,170 | +$444.14K |
| 2026-07-08 | TANG CAPITAL MANAGEMENT LLC | 10%+ Owner | Buy | +114,420 | +$283.73K |
| 2026-07-06 | Steven Gillis | 10%+ Owner | MIXED | — | −$116.80K |
| 2026-07-06 | ARCH Venture Fund IX Overage, L.P. | 10%+ Owner | MIXED | — | −$186.88K |
| 2026-07-02 | TANG CAPITAL MANAGEMENT LLC | 10%+ Owner | Buy | +214,926 | +$537.76K |
| 2026-06-29 | TANG CAPITAL MANAGEMENT LLC | 10%+ Owner | Buy | +572,666 | +$1.43M |
| 2026-06-15 | James Christensen | Director | A | +32,000 deriv. | — |
| 2026-06-15 | Jennifer Lew | Director | A | +32,000 deriv. | — |
| 2026-06-15 | Nancy Whiting | Director | A | +32,000 deriv. | — |
| 2026-06-15 | Jonathan E Lim | Director | A | +48,000 deriv. | — |
| 2026-01-26 | David A Hinkle | See Remarks | A | +140,000 deriv. | — |
| 2026-01-26 | Christian Hassig | Chief Scientific Officer | A | +230,000 deriv. | — |
| 2026-01-26 | Jessica Oien | See Remarks | A | +220,000 deriv. | — |
| 2026-01-26 | Zachary Hornby | President & CEO | A | +600,000 deriv. | — |
| 2026-01-26 | Robert Doebele | Chief Medical Officer | A | +230,000 deriv. | — |
| 2025-06-23 | Jonathan E Lim | Director | A | +24,000 deriv. | — |
| 2025-06-23 | Jennifer Lew | Director | A | +16,000 deriv. | — |
| 2025-06-23 | James Christensen | Director | A | +16,000 deriv. | — |
| 2025-06-23 | Kristina Burow | Director | A | +16,000 deriv. | — |
| 2025-06-23 | Nancy Whiting | Director | A | +16,000 deriv. | — |
| 2025-06-23 | Christine Brennan | Director | A | +16,000 deriv. | — |
| 2025-02-03 | Robert Doebele | Chief Medical Officer | A | +180,000 deriv. | — |
| 2025-01-23 | Jessica Oien | See Remarks | A | +90,000 deriv. | — |
| 2025-01-23 | David A Hinkle | See Remarks | A | +65,000 deriv. | — |
| 2025-01-23 | Christian Hassig | Chief Scientific Officer | A | +95,000 deriv. | — |
| 2025-01-23 | Zachary Hornby | President & CEO | A | +295,000 deriv. | — |
| 2024-08-20 | Zachary Hornby | President & CEO | MIXED | — | — |
| 2024-08-20 | Christian Hassig | Chief Scientific Officer | MIXED | — | — |
| 2024-08-20 | Jessica Oien | See Remarks | MIXED | — | — |
| 2024-08-20 | Jami Rubin | Chief Financial Officer | MIXED | — | — |
| 2024-08-20 | Klaus W. Wagner | Chief Medical Officer | MIXED | — | — |
| 2024-08-20 | Neil Abdollahian | Chief Business Officer | MIXED | — | — |
| 2024-06-20 | Jonathan E Lim | Director | A | +6,610 deriv. | — |
| 2024-04-04 | Kristina Burow | Director | MIXED | +2,625,721 | +$3.20M |
| 2024-04-04 | Jonathan E Lim | Director | C | +525,274 | — |
| 2024-04-04 | ARCH Venture Partners IX, L.P. | 10%+ Owner | MIXED | +21,005,768 | +$25.60M |
| 2024-04-04 | Robert Nelsen | 10%+ Owner | MIXED | +10,502,884 | +$12.80M |
| 2024-04-04 | RA CAPITAL MANAGEMENT, L.P. | 10%+ Owner | MIXED | +10,903,155 | +$25.00M |
| 2024-04-02 | Wellington Biomedical Innovation Master Investors (Cayman) I L.P. | 10%+ Owner | C | +556,233 | — |
| 2024-03-29 | Neil Abdollahian | Chief Business Officer | A | +23,191 deriv. | — |
| 2024-03-29 | Zachary Hornby | President & CEO | A | +162,343 deriv. | — |
| 2024-03-29 | Jennifer Lew | Director | A | +13,219 deriv. | — |
| 2024-03-29 | Klaus W. Wagner | Chief Medical Officer | A | +41,745 deriv. | — |
| 2024-03-29 | Kristina Burow | Director | A | +26,438 deriv. | — |
| 2024-03-29 | Jami Rubin | Chief Financial Officer | A | +32,468 deriv. | — |
| 2024-03-29 | James Christensen | Director | A | +13,219 deriv. | — |
| Insider | Role | Shares Held | Value |
|---|---|---|---|
| TANG CAPITAL MANAGEMENT LLC | 10%+ Owner | 2,958,820 | $7.13M |
| Kevin Tang | 10%+ Owner | 2,840,635 | $6.85M |
| ARCH Venture Fund IX Overage, L.P. | 10%+ Owner | 1,181,766 | $2.85M |
| Steven Gillis | 10%+ Owner | 828,570 | $2.00M |
| Kristina Burow | Director | 828,570 | $2.00M |
| Jonathan E Lim | Director | 653,479 | $1.57M |
Form 4 reports a change in beneficial ownership by an officer, director or 10%+ holder, and must be filed within two business days of the transaction — so this is close to real time, unlike the 45-day-lagged 13F institutional data.
Transaction codes matter more than the raw buy/sell count. Code P is an open-market purchase — an insider choosing to buy with their own money, which is the signal most research treats as informative. Code S is a sale, but sales are frequently pre-scheduled under a 10b5-1 plan or cover tax withholding on vesting equity, so a run of sales often says nothing directional. Codes A and M are grants and option exercises rather than open-market decisions.
Full filing history and per-insider positions are on the BOLD quote page; the site-wide leaderboard is on the insider transactions hub.
Market data may be delayed, incomplete, or inaccurate. Not a recommendation to buy, sell, or hold any security. Verify quotes with your broker before trading. See Terms §17.