Special Meeting of Stockholders to Approve Plan of Dissolution Scheduled for Friday, May 10, 2024 at 10:00 a.m. Eastern Standard Time

CAMBRIDGE, Mass.--(BUSINESS WIRE)--Merrimack Pharmaceuticals, Inc. (Nasdaq: MACK) ("Merrimack" or the "Company") today announced that it has received a $225 million payment which was due from Ipsen, S.A. as a result of its receipt of approval from the U.S. Food and Drug Administration, or FDA, to market ONIVYDE as a first-line treatment of metastatic adenocarcinoma on the pancreas.

Merrimack's Board of Directors has evaluated the likelihood of receiving additional milestone payments under the Ipsen Agreement and from the 2019 Agreement with Elevation Oncology and has concluded that it is unlikely that any additional milestone payments from either agreement will become payable. We have announced a special meeting of stockholders on May 10, 2024 to approve a Plan of Dissolution which includes plans for a liquidating dividend payable to stockholders. We currently anticipate the initial liquidating dividend to be in the range of between approximately $14.68 and $15.30 per share. The Plan of Dissolution will include establishment of a liquidating trust for the benefit of stockholders in the unlikely event that Merrimack might receive any future milestone payments from Ipsen or Elevation Technology.

IMPORTANT ADDITIONAL INFORMATION AND WHERE TO FIND IT

In connection with the proposed liquidation and Dissolution of the Company (the "Dissolution") and the Plan of Dissolution, the Company filed a definitive proxy statement (the "Proxy Statement") with the Securities and Exchange Commission (the "SEC") on March 21, 2024. BEFORE MAKING ANY VOTING DECISION, INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THE DEFINITIVE PROXY STATEMENT, ANY AMENDMENTS OR SUPPLEMENTS THERETO, ANY OTHER SOLICITING MATERIALS AND ANY OTHER DOCUMENTS TO BE FILED WITH THE SEC IN CONNECTION WITH THE PROPOSED DISSOLUTION, THE PLAN OF DISSOLUTION AND RELATED MATTERS, AND/OR INCORPORATED BY REFERENCE IN THE PROXY STATEMENT WHEN THEY BECOME AVAILABLE BECAUSE THEY CONTAIN OR WILL CONTAIN IMPORTANT INFORMATION ABOUT MERRIMACK PHARMACEUTICALS, INC., THE PROPOSED DISSOLUTION, THE PLAN OF DISSOLUTION AND RELATED MATTERS. Stockholders may obtain a free copy of the Proxy Statement and the other relevant materials (when they become available), and any other documents filed by the Company with the SEC, at the SEC's website at http://www.sec.gov or on the "Investors" section of the Company's website at .

Participants in the Solicitation

The Company and its executive officers and directors may be deemed to be participants in the solicitation of proxies from its stockholders with respect to the proposed Dissolution, the Plan of Dissolution and related matters, and any other matters to be voted on at the Special Meeting. Information regarding the names, affiliations and direct or indirect interests, by security holdings or otherwise, of such directors and executive officers in the solicitation are included in the Proxy Statement. Additional information regarding such directors and executive officers, and other important Company information, are included in the Company's Annual Report on Form 10-K for the year ended December 31, 2023, which was filed with the SEC on March 9, 2024, as amended by a Form 10-K/A and a Proxy Statement for its Special Meeting of Stockholders, each of which was filed with the SEC on March 21, 2024.

Information regarding the persons who may, under SEC rules, be deemed participants in the solicitation of proxies of the Company's stockholders in connection with the proposed Dissolution, the Plan of Dissolution and related matters are forth in the Proxy Statement. These documents will be available free of charge as described in the preceding section.