SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person* 22NW GP, Inc. (Last) (First) (Middle) 1455 NW LEARY WAY, SUITE 400 (Street) SEATTLE WA 98107 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 07/24/2019	3. Issuer Name and Ticker or Trading Symbol MERRIMACK PHARMACEUTICALS INC [ MACK ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) X Other (specify below) See Explanation of Responses	5. If Amendment, Date of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock(1)	1,241,896	I	By: 22NW Fund, LP(2)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. The Reporting Person may be deemed to be a member of a Section 13(d) group that collectively beneficially owns more than 10% of the Issuer's outstanding shares of Common Stock.The Reporting Person disclaims beneficial ownership of the securities of the Issuer owned directly by other members of the Section 13(d) group and this report shall not be deemed an admission that the Reporting Person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose. Further, the Reporting Person expressly disclaims beneficial ownership of the securities reported herein except to the extent of its pecuniary interest therein.

2. Securities owned directly by 22NW Fund, LP ("22NW Fund"). The Reporting Person, as the general partner of 22NW, LP, the investment adviser to 22NW Fund, may be deemed to beneficially own the securities owned directly by 22NW Fund.

	22NW GP, Inc., By: /s/ Aron R. English, President and Sole Shareholder	07/25/2019
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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