Common Stock, par value $0.001 per share

Astria Therapeutics, Inc.

22 Boston Wharf Road, Boston, MA, 02210

The persons filing this Statement are Magnetar Financial LLC, a Delaware limited liability company ("Magnetar Financial"), Magnetar Capital Partners LP, a Delaware limited partnership ("Magnetar Capital Partners"), Supernova Management LLC, a Delaware limited liability company ("Supernova Management"), and David J. Snyderman ("Mr. Snyderman") (collectively, the "Reporting Persons"). This Statement relates to Shares held for the accounts of each of (i) Magnetar PRA Master Fund Ltd ("PRA Master Fund"); (ii) Magnetar Systematic Multi-Strategy Master Fund Ltd, ("Systematic Master Fund"); (iii) Magnetar Relative Value Master Fund Ltd, ("Relative Value Master Fund"); all Cayman Islands exempted companies and (iv) two Managed Accounts for the client of Magnetar Asset Management LLC ("the Managed Account"), collectively (the "Funds"). Magnetar Financial is a Securities and Exchange Commission ("SEC") registered investment adviser under Section 203 of the Investment Advisers Act of 1940, as amended, and manager of investment funds and managed accounts. Magnetar Financial serves as investment adviser to each of the Funds. In such capacity, Magnetar Financial exercises voting and investment power over the Shares held for the accounts of each of the Funds. Magnetar Capital Partners serves as the sole member and parent holding company of Magnetar Financial. Supernova Management is the general partner of Magnetar Capital Partners. The administrative manager of Supernova Management is Mr. Snyderman. Magnetar Asset Management LLC ("Magnetar Asset Management") is an SEC registered investment adviser and an affiliate of Magnetar Financial. Magnetar Capital Partners serves as the sole member and parent holding company of Magnetar Asset Management.

The business address of each of the Reporting Persons is 1603 Orrington Avenue, 13th Floor, Evanston, Illinois 60201.

Each of the Funds is a private investment fund; Magnetar Financial is a privately-held SEC registered investment adviser and manager of investment funds; Magnetar Capital Partners is a privately-held limited partnership and serves as the sole member and parent holding company of Magnetar Financial; Supernova Management is a privately-held limited liability company and is the general partner of Magnetar Capital Partners; and Mr. Snyderman is a citizen of the United States of America, manager of Supernova Management and Chief Executive Officer of Magnetar Financial.

None of the Reporting Persons has, during the last five years, been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction as a result of which such Reporting Person was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

Magnetar Financial is a Delaware limited liability company. Magnetar Capital Partners is a Delaware limited partnership. Supernova Management is a Delaware limited liability company. Mr. Snyderman is a citizen of the United States of America.

The Company reported in their Form 8-K Report filed October 14, 2025, that 56,434,894 shares were outstanding as of October 10, 2025. As of the close of business October 22, 2025, each of the Reporting Persons may have been deemed to have beneficial ownership of 3,312,202 Shares, which consisted of (i) 1,507,698 Shares held for the benefit of PRA Master Fund, (ii) 776,947 Shares held for the benefit of Systematic Master Fund, (iii) 211,374 Shares held for the benefit of Relative Value Master Fund, and (iv) 816,183 Shares held for the benefit of the Managed Accounts, and all such Shares represented beneficial ownership of approximately 5.87% of the Shares.

As of the close of business October 22, 2025, each of the Reporting Persons may have been deemed to have beneficial ownership of 3,312,202 Shares, which consisted of (i) 1,507,698 Shares held for the benefit of PRA Master Fund, (ii) 776,947 Shares held for the benefit of Systematic Master Fund, (iii) 211,374 Shares held for the benefit of Relative Value Master Fund, and (iv) 816,183 Shares held for the benefit of the Managed Accounts, and all such Shares represented beneficial ownership of approximately 5.87% of the Shares.

Except as set forth on Schedule A attached hereto and Item 6, the Funds had no transactions in the Shares during the 60 days preceding the date of filing of this Statement. All of the transactions set forth on Schedule A attached hereto were effected in the ordinary course of business of Magnetar Financial for the accounts of each of the Funds. The transactions in the Shares set forth on Schedule A were effected in open market transactions on the NASDAQ and various other trading markets. As disclosed by the Company in the Form 8K filed with the SEC on October 14, 2025: Agreement and Plan of Merger On October 14, 2025, Astria Therapeutics, Inc., a Delaware corporation ("Astria"), BioCryst Pharmaceuticals, Inc., a Delaware corporation ("BioCryst"), and Axel Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of BioCryst ("Merger Sub"), entered into an Agreement and Plan of Merger (the "Merger Agreement"). Pursuant to the Merger Agreement, and subject to the satisfaction or waiver of the conditions specified therein, at the Effective Time (as defined below), Merger Sub will merge with and into Astria, with Astria surviving the Merger as a wholly owned subsidiary of BioCryst (the "Merger"). Merger Consideration Subject to the terms and conditions of the Merger Agreement, at the effective time of the Merger (the "Effective Time"), each share of common stock, par value $0.001 per share, of Astria ("Astria Common Stock") issued and outstanding immediately prior to the Effective Time (subject to certain exceptions, including shares of Astria Common Stock owned by stockholders of Astria who have not voted in favor of the adoption of the Merger Agreement and have properly exercised appraisal rights in accordance with Section 262 of the General Corporation Law of the State of Delaware) will be converted into the right to receive (i) 0.59 (the "Exchange Ratio") of a share of common stock, par value $0.01 per share, of BioCryst ("BioCryst Common Stock") and, if applicable, cash in lieu of fractional shares, and (ii) $8.55 in cash, without interest (the "Per Share Cash Amount"), subject to adjustment as described below and subject to applicable withholding taxes (the consideration described in the foregoing clauses (i) and (ii), collectively, the "Merger Consideration").

No other person is known by the Reporting Persons to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, any Shares that are beneficially owned by the Reporting Persons.

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