0001104659-13-055066 Sample Contracts

MERRIMACK PHARMACEUTICALS, INC. AND WELLS FARGO BANK, NATIONAL ASSOCIATION, as Trustee FIRST SUPPLEMENTAL INDENTURE Dated as of July 17, 2013 4.50% Convertible Senior Notes due 2020

First Supplemental Indenture • July 18th, 2013 • Merrimack Pharmaceuticals Inc • Pharmaceutical preparations

• Contract Type
  First Supplemental Indenture
• Filed
  July 18th, 2013
• Company
  Merrimack Pharmaceuticals Inc
• Industry
  Pharmaceutical preparations

FIRST SUPPLEMENTAL INDENTURE dated as of July 17, 2013 between MERRIMACK PHARMACEUTICALS, INC., a Delaware corporation, as issuer (the “Issuer,” as more fully set forth in Section 2.01) and WELLS FARGO BANK, NATIONAL ASSOCIATION, a national banking association, as trustee (the “Trustee,” as more fully set forth in Section 2.01).