Form 4 Filing for Boundless Bio, Inc.

This filing details several non-derivative transactions by TANG CAPITAL MANAGEMENT LLC and TANG KEVIN, both significant owners of Boundless Bio, Inc. (BOLD). The transactions, all purchases of common stock, occurred between October 16, 2026, and October 20, 2026. On October 16, 118,185 shares were acquired at a weighted average price of $2.34. Subsequent purchases on October 19 included 12,790 shares at $2.34 and 18,279 shares at $2.33. The final transaction on October 20 involved the acquisition of 220 shares at $2.37. These transactions resulted in a total post-transaction ownership of 2,990,109 shares for TANG CAPITAL MANAGEMENT LLC. Footnote 1 indicates that the reporting persons have paid $1,723.10 in disgorgeable profit related to these purchases. Footnote 3 provides details on the beneficial ownership structure of the reporting persons.