|Issuer:||MERRIMACK PHARMACEUTICALS INC (MACK)|
|Original Submission Date:|
NIELSEN ULRIK B.
C/O MERRIMACK PHARMACEUTICALS, INC.
ONE BROADWAY 14TH FLOOR CAMBRIDGE, MA 02142
|Title of Security||Transaction Date||2a. Deemed Execution Date||Transaction Code||Shares||Acquired or Disposed||Price per share||5. Amount of Securities Beneficially Owned Following Reported Transaction||6. Ownership Form Direct or Indirect||Nature of Indirect Ownership|
|Title of Derivative Security||Conversion or Exercise Price of Derivative Security||Transaction Date||Deemed Execution Date||Transaction Code||Number of Derivative Securities Acquired (A) or Disposed of (D)||Date Exercisable||Expiration Date||Title and Amount of Securities Underlying Derivative Security||Price of Derivative Security||Number of derivative Securities Beneficially Owned Following Reported Transaction(s)||Ownership Form: Direct (D) or Indirect (I)||Nature of Indirect Beneficial Ownership|
|STOCK OPTION (RIGHT TO BUY)||5.2||2022-06-06||deemed execution date||A||7,000 (a)||2032-06-05||common stock 7,000||$5.20||21,000||direct|
|f1||this option vests as to 1/4th of the total number of shares on 7/1/22 and an additional 1/4th of the total number of shares at the end of each successive three month period thereafter until 4/1/23.|