X0609 4 2026-10-16 0001782303 Boundless Bio, Inc. BOLD 0001178579 TANG KEVIN false 4747 EXECUTIVE DRIVE SUITE 210 SAN DIEGO CA 92121 false false true false 0001232621 TANG CAPITAL MANAGEMENT LLC false 4747 EXECUTIVE DRIVE SUITE 210 SAN DIEGO CA 92121 0 0 1 0 0 Common Stock 2026-10-16 4 P 0 118185 2.34 A 2958820 I See Footnote Common Stock 2026-10-19 4 P 0 12790 2.34 A 2971610 I See Footnote Common Stock 2026-10-19 4 P 0 18279 2.33 A 2989889 I See Footnote Common Stock 2026-10-20 4 P 0 220 2.37 A 2990109 I See Footnote The Reporting Persons have delivered to the Issuer the full amount of the disgorgeable profit arising the purchases reported herein, in the amount of $1,723.10. The prices reported are weighted-average prices. These shares were purchased in multiple transactions at prices ranging from $2.31 to $2.35. The Reporting Persons undertake to provide the Issuer, any security holder of the Issuer or the SEC staff, upon request, all information regarding the number of shares purchased at each price within the range set forth in Footnotes 2 and 4 through 6. Tang Capital Partners, LP ("TCP") beneficially owns 688,494 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 937,213 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 688,487 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 675,915 shares. Kevin Tang is the sole manager of Tang Capital Management, LLC, which is the general partner of TCP and TCPI. Kevin Tang is the sole director and Chief Executive Officer of TCP III and TCP IV, which are indirectly wholly owned by TCP. Mr. Tang has a pecuniary interest in the shares beneficially held by TCP, TCPI, TCP III and TCP IV. These shares were purchased in multiple transactions at prices ranging from $2.31 to $2.35. These shares were purchased in multiple transactions at prices ranging from $2.32 to $2.35. These shares were purchased in multiple transactions at prices ranging from $2.33 to $2.40. Kevin Tang 2026-10-20 Kevin Tang, Manager 2026-10-20