Zachary Hornby - 23 Jan 2026 Form 4 Insider Report for Boundless Bio, Inc. (BOLD)

Role
President & CEO, Director
Signature
/s/ Jessica Oien, Attorney-in- Fact for Zachary Hornby
Issuer symbol
BOLD
Transactions as of
23 Jan 2026
Net transactions value
$0
Form type
4
Filing time
26 Jan 2026, 07:00:04 UTC
Previous filing
23 Jan 2025
SEC
View on sec.gov

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
Hornby Zachary President & CEO, Director C/O BOUNDLESS BIO, INC., 10955 ALEXANDRIA WAY, SUITE 100, SAN DIEGO /s/ Jessica Oien, Attorney-in- Fact for Zachary Hornby 23 Jan 2026 0001602227

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Underlying Class Amount Exercise Price Ownership Footnotes
transaction BOLD Stock Option (right to buy) Award $0 +600,000 $0.000000 600,000 23 Jan 2026 Common Stock 600,000 $1.26 Direct F1
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id Content
F1 The vesting commencement date is January 1, 2026. The stock option vests in 48 substantially equal monthly installments. Accordingly, 1/48th of this stock option vests on February 1, 2026, and monthly thereafter.