ARCH-linked holders trade 16,000 Boundless Bio shares
Boundless Bio, Inc. reported insider activity involving entities affiliated with ARCH Venture funds and investment committee member Kristina Burow.
Accepted by SEC EDGAR
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Form Type
4
Rhea-AI Filing Summary
Boundless Bio, Inc. reported insider activity involving entities affiliated with ARCH Venture funds and investment committee member Kristina Burow. On July 1, 2026, a cashless stock option exercise for 16,000 shares of common stock at $1.03 per share was completed, followed by an open-market sale of 16,000 shares at $2.49 per share, with net proceeds remitted to ARCH funds. The filing also shows indirect holdings of 1,181,766, 828,570 and 683,759 shares of common stock as of that date.
Insider Trade Summary
Exercise and Sale: 16,000 shares ($23K approx. pre-tax spread)
Exercise and Sale
3 txns
Insider
CRANDELL KEITH, BYBEE CLINTON, NELSEN ROBERT, GILLIS STEVEN, Burow Kristina
Role
10% Owner | 10% Owner | 10% Owner | 10% Owner | 10% Owner
Sold
16,000 shs ($40K)
Approx. gross sale proceeds
$40K
Approx. exercise cost
$16K
Approx. pre-tax spread
$23K
| Type | Security | Shares | Price | Value |
|---|---|---|---|---|
| Exercise | Stock Option (right to buy) | 16,000 | $0.00 | $0.00 |
| Exercise | Common Stock | 16,000 | $1.03 | $16K |
| Sale | Common Stock | 16,000 | $2.49 | $40K |
| Holding | Common Stock | -- | -- | -- |
| Holding | Common Stock | -- | -- | -- |
| Holding | Common Stock | -- | -- | -- |
Holdings After Transaction:
Stock Option (right to buy) — 0 contracts (Indirect, See footnote);
Common Stock — 0 shares (Indirect, See footnote);
Common Stock — 2,694,095 shares (Indirect, See footnotes)
Footnotes (7)
- F1. Represents a cashless stock option exercise by Kristina Burow. The net proceeds of such exercise were remitted to ARCH Venture Fund IX, L.P. (ARCH IX), ARCH Venture Fund IX Overage, L.P. (ARCH IX Overage), and ARCH Venture Fund X, L.P. (AVF X Overage LP). The stock option was granted to Kristina Burow in connection with her service on the board of directors of the Issuer.
- F2. Represents shares held directly by ARCH Venture Fund IX, L.P. (ARCH IX). ARCH Venture Partners IX, L.P. (AVP IX LP) is the sole general partner of ARCH IX.
- F3. Represents shares held directly by ARCH Venture Fund IX Overage, L.P. (ARCH IX Overage). ARCH Venture Partners IX Overage, L.P. (AVP IX Overage LP) is the sole general partner of ARCH IX Overage.
- F4. ARCH Venture Partners IX, LLC (AVP IX LLC) is the sole general partner of each of AVP IX LP and AVP IX Overage LP. Keith Crandell, Robert Nelsen and Clinton Bybee are managing directors of AVP IX LLC (the AVP IX MDs). AVP IX LP and AVP IX Overage LP may be deemed to beneficially own the shares held by ARCH IX and ARCH IX Overage, respectively, AVP IX LLC may be deemed to beneficially own the shares held by ARCH IX and ARCH IX Overage, and each of the AVP IX MDs may be deemed to share the power to direct the disposition and vote of the shares held by ARCH IX and ARCH IX Overage. AVP IX LP, AVP IX Overage LP, AVP IX LLC, and the AVP IX MDs each disclaim beneficial ownership except to to the extent of any pecuniary interest therein, if any.
- F5. Represents shares held directly by ARCH Venture Fund X Overage, L.P. (ARCH X Overage). ARCH Venture Partners X Overage, L.P. (AVP X Overage LP) is the sole general partner of ARCH X Overage.
- F6. ARCH Venture Partners X, LLC (AVP X LLC) is the sole general partner of AVP X Overage LP. Keith Crandell, Kristina Burow, Robert Nelsen and Steven Gillis are members of the investment committee of AVP X LLC (the AVP X Committee Members). AVP X Overage LP may be deemed to beneficially own the shares held by ARCH X Overage, AVP X LLC may be deemed to beneficially own the shares held by ARCH X Overage, and each of the AVP X Committee Members may be deemed to share the power to direct the disposition and vote of the shares held by ARCH X Overage. AVP X Overage LP, AVP X LLC, and the AVP X Committee Members each disclaim beneficial ownership except to the extent of any pecuniary interest therein, if any.
- F7. The stock option vested in substantially equal monthly installments over the 11 months following June 23, 2025. The final unvested portion vested on June 15, 2026, the date of the Issuer's 2026 annual meeting of stockholders.
Key Figures
Shares sold: 16,000 shares
Sale price: $2.49 per share
Option exercise size: 16,000 shares
+5 more
8 metrics
Shares sold
16,000 shares
Open-market sale of common stock on July 1, 2026
Sale price
$2.49 per share
Price for 16,000 Boundless Bio common shares sold
Option exercise size
16,000 shares
Common stock acquired via stock option exercise
Option exercise price
$1.03 per share
Exercise price for stock option granted to Kristina Burow
Exercise date
July 1, 2026
Date of option exercise and related sale
Option expiration
June 22, 2035
Expiration date of the exercised stock option
Indirect holding block
1,181,766 shares
Indirect common stock holdings reported as of July 1, 2026
Net share change
-16,000 shares
Net buy/sell direction across reported transactions
Key Terms
cashless stock option exercise, beneficially own, pecuniary interest, annual meeting of stockholders, +1 more
5 terms
cashless stock option exercise financial
"Represents a cashless stock option exercise by Kristina Burow."
beneficially own financial
"may be deemed to beneficially own the shares held by ARCH IX"
Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.
pecuniary interest financial
"each disclaim beneficial ownership except to the extent of any pecuniary interest"
annual meeting of stockholders regulatory
"vested on June 15, 2026, the date of the Issuer's 2026 annual meeting of stockholders."
stock option financial
"The stock option was granted to Kristina Burow in connection with her service"
A stock option is a contract that gives you the right to buy or sell a company's stock at a specific price within a certain time frame. People use them to potentially make money if the stock's price moves favorably or to protect against losses. It's like holding a coupon that can be used to buy or sell stock at a set price later on.
AI-generated analysis. How Rhea-AI works. Not financial advice.
