Boundless Bio, Inc.

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds.

(a)

Recent Sales of Unregistered Securities.

None.

(b)

Use of Proceeds.

On March 27, 2024, our registration statement on Form S-1 (File No. 333-277696), as amended, was declared effective by the SEC for our IPO. At the closing of the IPO on April 2, 2024, we sold 6,250,000 shares of common stock at a public offering price of $16.00 per share and received gross proceeds of $100.0 million, which resulted in net proceeds to us of approximately $87.7 million, after deducting underwriting discounts and commissions and other offering expenses.

As of September 30, 2026, we had used approximately $45.6 million of the net proceeds to fund our operations, including clinical development activities for BBI-940 and the KOMODO-1 trial, the wind down of the POTENTIATE and STARMAP trials, costs associated with the termination of our facility leases, and severance and transaction costs incurred in connection with the Merger. Our actual and planned use of the net proceeds has changed from that described in the IPO prospectus as a result of portfolio prioritization decisions that focused our activity on the BBI-940 program, although the early clinical data for BBI-940 did not support continuing to advance the program.

On June 22, 2026, we entered into the Merger Agreement with Serapha, as amended on August 28, 2026, as described in Note 1. Prior to the Closing, we expect to declare and pay a cash dividend to pre-merger stockholders of approximately $44 to $48 million to distribute excess net cash, subject to adjustment based on our net cash at closing as defined in the Merger Agreement, which would represent a significant use of our remaining net proceeds.

The amounts and timing of our actual expenditures may vary significantly depending on numerous factors, including the outcome of the pending merger and the factors described in Item 1A, “Risk Factors,” in our 2025 10-K, as updated by subsequent filings, including in Item 1A, “Risk Factors,” in our Q2 2026 10-Q. Our management has broad discretion in the application of the net proceeds.

(c)

Issuer Purchases of Equity Securities.

None.