Material Event (Form 8-K)

As previously disclosed, on May 31, 2026, the Rallybio Corporation, a Delaware corporation (the "Company"), entered into an Agreement and Plan of Merger and Reorganization (the "Merger Agreement") with Avenzo Therapeutics, Inc., a Delaware corporation ("Avenzo"), and Farmington Merger Sub, Inc., a Delaware corporation and wholly-owned subsidiary of the Company ("Merger Sub"), pursuant to which, among other matters, and subject to the satisfaction or waiver of the conditions set forth in the Merger Agreement, Merger Sub will merge with and into Avenzo, with Avenzo continuing as a wholly owned subsidiary of the Company and the surviving corporation of the merger (the "Merger").

On October 25, 2026, the Company's board of directors (the "Board") declared a special cash distribution to its stockholders in connection with the Merger (the "Cash Distribution"). The Cash Distribution, which the Company estimates to be an aggregate of $82.7 million, or an estimated $13.56 per share, will be payable in cash to the stockholders and pre-funded warrant holders of record as of November 5, 2026, with such date subject to change based on the date of the stockholder meeting (the "Record Date"), and further subject to the Nasdaq due bill procedures described below, based on their holdings as of the Record Date and during the Due Bill Period (as defined below). The estimated Cash Distribution is based on the Company's good faith calculation of the amount by which the Company's net cash, as determined pursuant to the terms of the Merger Agreement prior to the closing of the Merger, will exceed $0. The estimated per share distribution is based on 6,378,168 shares of common stock and common stock equivalents outstanding as of October 21, 2026. The total actual distribution of the amount of the Cash Distribution will be deposited with the Company's transfer agent on November 5, 2026 and is scheduled to be further distributed on November 13, 2026 (the "Distribution Payment Date") and may be higher or lower than the estimated amount. The transfer agent will distribute the Cash Distribution to stockholders and warrant holders within a few days following the Distribution Payment Date.

Because the Cash Distribution per share exceeds 25% of the Company's stock price on the declaration date, it is subject to an ex-dividend date of the day of the Closing of the Merger. Accordingly, Nasdaq is expected to set November 6, 2026 as the ex-dividend date for the Cash Distribution.

In addition, the Company understands that trades of the Company's common stock entered into during the due bill period, which is expected to begin November 4, 2026 (the business day before the Record Date) and continue through November 6, 2026 (the "Due Bill Period"), will have a due bill attached for the Cash Distribution. Due bills obligate sellers of the Company's common stock to deliver the Cash Distribution to the buyer of such common stock during the Due Bill Period. This means that persons who purchase the Company's common stock during the Due Bill Period (even if the trade will settle after the Due Bill Period) are entitled to receive the Cash Distribution, and persons who sell the stock during the Due Bill Period (even if the trade will settle after the Due Bill Period) are not entitled to the Cash Distribution. Accordingly, if an investor wishes to receive the Cash Distribution, the investor will need to hold the securities through and including November 6, 2026. The due bill obligations are settled customarily between the brokers representing the buyers and sellers of the stock. Buyers and sellers of the Company's common stock should consult with their broker before trading to ensure they understand the effect of Nasdaq's due bill procedures. The Company has no obligations for either the amount of the due bill or the processing of the due bill.

Payment of the Cash Distribution is conditioned upon the receipt of the Required Company Stockholder Vote (as defined in the Merger Agreement) at the Company's annual meeting of stockholders scheduled to be held at 10:00 a.m. Eastern Time on November 4, 2026. Closing of the Merger is expected to occur on or about November 6, 2026, assuming that the transaction is approved by the Company's stockholders and the satisfaction or waiver of all conditions under the Merger Agreement.

On October 25, 2026, the Board also fixed the close of business on the Record Date as the record date for the Company's previously announced distribution of contingent value rights to holders of record of the Company's common stock in connection with the Merger.