# EDGAR Filing Document

**Accession Number:** 0001640809
**File Stem:** 0000921895-23-000448
**Filing Date:** 2023-2
**Character Count:** 24899
**Document Hash:** 7f60fe2e82f2302c38f79b469342a24c
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000921895-23-000448.hdr.sgml**: 20230213

**ACCESSION NUMBER**: 0000921895-23-000448

**CONFORMED SUBMISSION TYPE**: SC 13G/A

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20230213

**DATE AS OF CHANGE**: 20230213

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** MERRIMACK PHARMACEUTICALS INC
- **CENTRAL INDEX KEY:** 0001274792
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **IRS NUMBER:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SC 13G/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-86778
- **FILM NUMBER:** 23618794

**BUSINESS ADDRESS:**
- **STREET 1:** ONE BROADWAY
- **STREET 2:** 14TH FLOOR
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
- **BUSINESS PHONE:** 617-441-1000

**MAIL ADDRESS:**
- **STREET 1:** ONE BROADWAY
- **STREET 2:** 14TH FLOOR
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** 22NW Fund, LP
- **CENTRAL INDEX KEY:** 0001640809
- **IRS NUMBER:** 473303449
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SC 13G/A

**BUSINESS ADDRESS:**
- **STREET 1:** 1455 NW LEARY WAY
- **STREET 2:** SUITE 400
- **CITY:** SEATTLE
- **STATE:** WA
- **ZIP:** 98107
- **BUSINESS PHONE:** 206-227-3078

**MAIL ADDRESS:**
- **STREET 1:** 1455 NW LEARY WAY
- **STREET 2:** SUITE 400
- **CITY:** SEATTLE
- **STATE:** WA
- **ZIP:** 98107

**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

**Washington, D.C. 20549**

**SCHEDULE 13G**

(Rule 13d-102)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO RULES 13d-1(b), (c), AND (d) AND AMENDMENTS THERETO FILED

PURSUANT TO RULE 13d-2(b)

(Amendment No. 3)<sup>1</sup>

<u> Merrimack Pharmaceuticals, Inc.</u> <br> (Name of Issuer)

---

| |
|:---|
| Common Stock, par value $0.01 per share |
| (Title of Class of Securities) |

---

<u> 590328209</u> <br> (CUSIP Number)

<u> December 31, 2022</u> <br> (Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

☐ Rule 13d-1(b)

☒ Rule 13d-1(c)

☐ Rule 13d-1(d)

1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, *see* the *Notes*).

CUSIP No. 590328209

---

| | | | | |
|:---|:---|:---|:---|:---|
| 1 | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON |
| |  | 22NW Fund, LP | 22NW Fund, LP | 22NW Fund, LP |
| 2 | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | (a) ☐ |
|  |  |  |  | (b) ☐ |
| 3 | &nbsp;&nbsp;SEC USE ONLY | &nbsp;&nbsp;SEC USE ONLY | &nbsp;&nbsp;SEC USE ONLY |  |
| 4 | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION |
| |  | DELAWARE | DELAWARE | DELAWARE |
| NUMBER OF |  | 5 | &nbsp;&nbsp;SOLE VOTING POWER | &nbsp;&nbsp;SOLE VOTING POWER |
| SHARES |  |  |  |  |
| BENEFICIALLY |  |  | 1015048 | 1015048 |
| OWNED BY |  | 6 | &nbsp;&nbsp;SHARED VOTING POWER | &nbsp;&nbsp;SHARED VOTING POWER |
| EACH |  |  |  |  |
| REPORTING |  |  | - 0 - | - 0 - |
| PERSON WITH |  | 7 | &nbsp;&nbsp;SOLE DISPOSITIVE POWER | &nbsp;&nbsp;SOLE DISPOSITIVE POWER |
|  |  |  | 1015048 | 1015048 |
|  |  | 8 | &nbsp;&nbsp;SHARED DISPOSITIVE POWER | &nbsp;&nbsp;SHARED DISPOSITIVE POWER |
|  |  |  | - 0 - | - 0 - |
| 9 | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON |
|  |  | 1015048 | 1015048 | 1015048 |
| 10 | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;☐ |
| 11 | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) |
|  |  | 7.6% | 7.6% | 7.6% |
| 12 | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON |
|  |  | PN | PN | PN |

---

CUSIP No. 590328209

---

| | | | | |
|:---|:---|:---|:---|:---|
| 1 | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON |
| |  | 22NW, LP | 22NW, LP | 22NW, LP |
| 2 | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | (a) ☐ |
|  |  |  |  | (b) ☐ |
| 3 | &nbsp;&nbsp;SEC USE ONLY | &nbsp;&nbsp;SEC USE ONLY | &nbsp;&nbsp;SEC USE ONLY |  |
| 4 | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION |
| |  | DELAWARE | DELAWARE | DELAWARE |
| NUMBER OF |  | 5 | &nbsp;&nbsp;SOLE VOTING POWER | &nbsp;&nbsp;SOLE VOTING POWER |
| SHARES |  |  |  |  |
| BENEFICIALLY |  |  | 1015048 | 1015048 |
| OWNED BY |  | 6 | &nbsp;&nbsp;SHARED VOTING POWER | &nbsp;&nbsp;SHARED VOTING POWER |
| EACH |  |  |  |  |
| REPORTING |  |  | - 0 - | - 0 - |
| PERSON WITH |  | 7 | &nbsp;&nbsp;SOLE DISPOSITIVE POWER | &nbsp;&nbsp;SOLE DISPOSITIVE POWER |
|  |  |  | 1015048 | 1015048 |
|  |  | 8 | &nbsp;&nbsp;SHARED DISPOSITIVE POWER | &nbsp;&nbsp;SHARED DISPOSITIVE POWER |
|  |  |  | - 0 - | - 0 - |
| 9 | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON |
|  |  | 1015048 | 1015048 | 1015048 |
| 10 | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;☐ |
| 11 | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) |
|  |  | 7.6% | 7.6% | 7.6% |
| 12 | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON |
|  |  | PN | PN | PN |

---

CUSIP No. 590328209

---

| | | | | |
|:---|:---|:---|:---|:---|
| 1 | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON |
| |  | 22NW Fund GP, LLC | 22NW Fund GP, LLC | 22NW Fund GP, LLC |
| 2 | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | (a) ☐ |
|  |  |  |  | (b) ☐ |
| 3 | &nbsp;&nbsp;SEC USE ONLY | &nbsp;&nbsp;SEC USE ONLY | &nbsp;&nbsp;SEC USE ONLY |  |
| 4 | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION |
| |  | DELAWARE | DELAWARE | DELAWARE |
| NUMBER OF |  | 5 | &nbsp;&nbsp;SOLE VOTING POWER | &nbsp;&nbsp;SOLE VOTING POWER |
| SHARES |  |  |  |  |
| BENEFICIALLY |  |  | 1015048 | 1015048 |
| OWNED BY |  | 6 | &nbsp;&nbsp;SHARED VOTING POWER | &nbsp;&nbsp;SHARED VOTING POWER |
| EACH |  |  |  |  |
| REPORTING |  |  | - 0 - | - 0 - |
| PERSON WITH |  | 7 | &nbsp;&nbsp;SOLE DISPOSITIVE POWER | &nbsp;&nbsp;SOLE DISPOSITIVE POWER |
|  |  |  | 1015048 | 1015048 |
|  |  | 8 | &nbsp;&nbsp;SHARED DISPOSITIVE POWER | &nbsp;&nbsp;SHARED DISPOSITIVE POWER |
|  |  |  | - 0 - | - 0 - |
| 9 | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON |
|  |  | 1015048 | 1015048 | 1015048 |
| 10 | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;☐ |
| 11 | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) |
|  |  | 7.6% | 7.6% | 7.6% |
| 12 | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON |
|  |  | OO | OO | OO |

---

CUSIP No. 590328209

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| | | | | |
|:---|:---|:---|:---|:---|
| 1 | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON |
| |  | 22NW GP, Inc. | 22NW GP, Inc. | 22NW GP, Inc. |
| 2 | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | (a) ☐ |
|  |  |  |  | (b) ☐ |
| 3 | &nbsp;&nbsp;SEC USE ONLY | &nbsp;&nbsp;SEC USE ONLY | &nbsp;&nbsp;SEC USE ONLY |  |
| 4 | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION |
| |  | DELAWARE | DELAWARE | DELAWARE |
| NUMBER OF |  | 5 | &nbsp;&nbsp;SOLE VOTING POWER | &nbsp;&nbsp;SOLE VOTING POWER |
| SHARES |  |  |  |  |
| BENEFICIALLY |  |  | 1015048 | 1015048 |
| OWNED BY |  | 6 | &nbsp;&nbsp;SHARED VOTING POWER | &nbsp;&nbsp;SHARED VOTING POWER |
| EACH |  |  |  |  |
| REPORTING |  |  | - 0 - | - 0 - |
| PERSON WITH |  | 7 | &nbsp;&nbsp;SOLE DISPOSITIVE POWER | &nbsp;&nbsp;SOLE DISPOSITIVE POWER |
|  |  |  | 1015048 | 1015048 |
|  |  | 8 | &nbsp;&nbsp;SHARED DISPOSITIVE POWER | &nbsp;&nbsp;SHARED DISPOSITIVE POWER |
|  |  |  | - 0 - | - 0 - |
| 9 | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON |
|  |  | 1015048 | 1015048 | 1015048 |
| 10 | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;☐ |
| 11 | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) |
|  |  | 7.6% | 7.6% | 7.6% |
| 12 | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON |
|  |  | CO | CO | CO |

---

CUSIP No. 590328209

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| | | | | |
|:---|:---|:---|:---|:---|
| 1 | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON | &nbsp;&nbsp;NAME OF REPORTING PERSON |
| |  | Aron R. English | Aron R. English | Aron R. English |
| 2 | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | &nbsp;&nbsp;CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP | (a) ☐ |
|  |  |  |  | (b) ☐ |
| 3 | &nbsp;&nbsp;SEC USE ONLY | &nbsp;&nbsp;SEC USE ONLY | &nbsp;&nbsp;SEC USE ONLY |  |
| 4 | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION | &nbsp;&nbsp;CITIZENSHIP OR PLACE OF ORGANIZATION |
| |  | USA | USA | USA |
| NUMBER OF |  | 5 | &nbsp;&nbsp;SOLE VOTING POWER | &nbsp;&nbsp;SOLE VOTING POWER |
| SHARES |  |  |  |  |
| BENEFICIALLY |  |  | 1015048 | 1015048 |
| OWNED BY |  | 6 | &nbsp;&nbsp;SHARED VOTING POWER | &nbsp;&nbsp;SHARED VOTING POWER |
| EACH |  |  |  |  |
| REPORTING |  |  | - 0 - | - 0 - |
| PERSON WITH |  | 7 | &nbsp;&nbsp;SOLE DISPOSITIVE POWER | &nbsp;&nbsp;SOLE DISPOSITIVE POWER |
|  |  |  | 1015048 | 1015048 |
|  |  | 8 | &nbsp;&nbsp;SHARED DISPOSITIVE POWER | &nbsp;&nbsp;SHARED DISPOSITIVE POWER |
|  |  |  | - 0 - | - 0 - |
| 9 | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON | &nbsp;&nbsp;AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON |
|  |  | 1015048 | 1015048 | 1015048 |
| 10 | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;☐ |
| 11 | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) | &nbsp;&nbsp;PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) |
|  |  | 7.6% | 7.6% | 7.6% |
| 12 | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON | &nbsp;&nbsp;TYPE OF REPORTING PERSON |
|  |  | IN | IN | IN |

---

CUSIP No. 590328209

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| | |
|:---|:---|
| **Item 1(a).** | **Name of Issuer:** |

---

Merrimack Pharmaceuticals, Inc., a Delaware corporation (the "Issuer").

---

| | |
|:---|:---|
| **Item 1(b).** | **Address of Issuer's Principal Executive Offices:** |

---

One Broadway, 14th Floor

Cambridge, MA 02142

---

| | |
|:---|:---|
| **Item 2(a).** | **Name of Person Filing:** |

---

This statement is filed by 22NW Fund, LP, a Delaware limited partnership ("22NW Fund"), 22NW, LP, a Delaware limited partnership ("22NW"), 22NW Fund GP, LLC, a Delaware limited liability company ("22NW GP"), 22NW GP, Inc., a Delaware S Corporation ("22NW Inc."), and Aron R. English. Each of the foregoing is referred to as a "Reporting Person" and collectively as the "Reporting Persons."

22NW serves as the investment manager of 22NW Fund. 22NW GP serves as the general partner of 22NW Fund. 22NW Inc. serves as the general partner of 22NW. Mr. English is the Portfolio Manager of 22NW, Manager of 22NW GP and President and sole shareholder of 22NW Inc. By virtue of these relationships, 22NW, 22NW GP, 22NW Inc. and Mr. English may be deemed to beneficially own the Shares (as defined below) owned directly by 22NW Fund.

---

| | |
|:---|:---|
| **Item 2(b).** | **Address of Principal Business Office or, if None, Residence:** |

---

The address of the principal office of each of the Reporting Persons is 1455 NW Leary Way, Suite 400, Seattle, Washington 98107.

---

| | |
|:---|:---|
| **Item 2(c).** | **Citizenship:** |

---

22NW Fund, 22NW, 22NW GP and 22NW Inc. are organized under the laws of the State of Delaware. Mr. English is a citizen of the United States of America.

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| | |
|:---|:---|
| **Item 2(d).** | **Title of Class of Securities:** |

---

Common Stock, $0.01 par value per share (the "Shares").

---

| | |
|:---|:---|
| **Item 2(e).** | **CUSIP Number:** |

---

590328209

CUSIP No. 590328209

**Item 3.** **If This Statement is Filed Pursuant to Rule 13d-1(b), or 13d-2(b) or (c), Check Whether the Person Filing is a:**

---

| | | |
|:---|:---|:---|
|  | &nbsp;&nbsp;/x/ | &nbsp;&nbsp;Not applicable. |
| &nbsp;&nbsp;(a) | &nbsp;&nbsp;/ / | &nbsp;&nbsp;Broker or dealer registered under Section 15 of the Exchange Act. |
| &nbsp;&nbsp;(b) | &nbsp;&nbsp;/ / | &nbsp;&nbsp;Bank as defined in Section 3(a)(6) of the Exchange Act. |
| &nbsp;&nbsp;(c) | &nbsp;&nbsp;/ / | &nbsp;&nbsp;Insurance company as defined in Section 3(a)(19) of the Exchange Act. |
| &nbsp;&nbsp;(d) | &nbsp;&nbsp;/ / | &nbsp;&nbsp;Investment company registered under Section 8 of the Investment Company Act. |
| &nbsp;&nbsp;(e) | &nbsp;&nbsp;/ / | &nbsp;&nbsp;An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E). |
| &nbsp;&nbsp;(f) | &nbsp;&nbsp;/ / | &nbsp;&nbsp;An employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F). |
| &nbsp;&nbsp;(g) | &nbsp;&nbsp;/ / | &nbsp;&nbsp;A parent holding company or control person in accordance with Rule 13d-1(b)(1)(ii)(G). |
| &nbsp;&nbsp;(h) | &nbsp;&nbsp;/ / | &nbsp;&nbsp;A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act. |
| &nbsp;&nbsp;(i) | &nbsp;&nbsp;/ / | &nbsp;&nbsp;A church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act. |
| &nbsp;&nbsp;(j) | &nbsp;&nbsp;/ / | &nbsp;&nbsp;Non-U.S. institution in accordance with Rule 240.13d-1(b)(1)(ii)(J). |
| &nbsp;&nbsp;(k) | &nbsp;&nbsp;/ / | &nbsp;&nbsp;Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K). If filing as a non-U.S. institution in accordance with Rule 240.13d-1(b)(1)(ii)(J), please specify the type of institution: ____ |

---

**Item 4.** **Ownership.**

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(a)** **Amount beneficially owned:** 

As of the close of business on December 31, 2022:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i) 22NW Fund directly owned 1,015,048 Shares.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii) Each of 22NW, as the investment manager of 22NW Fund, 22NW GP, as the general partner of 22NW Fund, 22NW
Inc., as the general partner of 22NW, and Mr. English, as the Portfolio Manager of 22NW, Manager of 22NW GP and President and sole shareholder
of 22NW Inc., may be deemed to beneficially own the 1,015,048 Shares owned directly by 22NW Fund.

The filing of this Schedule 13G shall not be construed as an admission that the Reporting Persons are, for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, the beneficial owners of any of the Shares reported herein that he or it does not directly own. Each of the Reporting Persons specifically disclaims beneficial ownership of the Shares reported herein that are not directly owned by such Reporting Person.

CUSIP No. 590328209

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(b)** **Percent of class:** 

The following percentages are based on 13,410,243 Shares outstanding as of November 1, 2022, which is the total number of Shares outstanding as reported in the Issuer's quarterly report on Form 10-Q filed with the Securities and Exchange Commission on November 3, 2022.

As of the close of business on December 31, 2022, each of 22NW Fund, 22NW, 22NW GP, 22NW Inc. and Mr. English may be deemed to beneficially own approximately 7.6% of the outstanding Shares.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**(c)** **Number of shares as to which such person has:** 

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i) Sole power to vote or to direct the vote:

See Cover Pages Items 5-9.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii) Shared power to vote or to direct the vote:

See Cover Pages Items 5-9.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iii) Sole power to dispose or to direct the disposition of:

See Cover Pages Items 5-9.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iv) Shared power to dispose or to direct the disposition of:

See Cover Pages Items 5-9.

**Item 5.** **Ownership of Five Percent or Less of a Class.**

Not Applicable.

**Item 6.** **Ownership of More than Five Percent on Behalf of Another Person.**

Not applicable.

**Item 7.** **Identification and Classification of the Subsidiary That Acquired the Security Being Reported on by the Parent Holding Company or Control Person.**

Not Applicable.

**Item 8.** **Identification and Classification of Members of the Group.**

See Exhibit 99.1 to the Schedule 13G filed by the Reporting Persons with the Securities and Exchange Commission on February 14, 2022.

CUSIP No. 590328209

**Item 9.** **Notice of Dissolution of Group.**

Not Applicable.

**Item 10.** **Certifications.**

By signing below each of the undersigned certifies that, to the best of its knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

CUSIP No. 590328209

<u>SIGNATURE</u>

After reasonable inquiry and to the best of his knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

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| | | | |
|:---|:---|:---|:---|
| &nbsp;&nbsp;Dated: February 13, 2023 | &nbsp;&nbsp;22NW FUND, LP | &nbsp;&nbsp;22NW FUND, LP | &nbsp;&nbsp;22NW FUND, LP |
|  | &nbsp;&nbsp;By: | &nbsp;&nbsp;22NW Fund GP, LLC<br> General Partner | &nbsp;&nbsp;22NW Fund GP, LLC<br> General Partner |
|  | &nbsp;&nbsp;By: | &nbsp;&nbsp;/s/ Aron R. English | &nbsp;&nbsp;/s/ Aron R. English |
|  |  | &nbsp;&nbsp;Name: | &nbsp;&nbsp;Aron R. English |
|  |  | &nbsp;&nbsp;Title: | &nbsp;&nbsp;Manager |

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| | | |
|:---|:---|:---|
| &nbsp;&nbsp;22NW, LP | &nbsp;&nbsp;22NW, LP | &nbsp;&nbsp;22NW, LP |
| &nbsp;&nbsp;By: | &nbsp;&nbsp;22NW GP, Inc.<br> General Partner | &nbsp;&nbsp;22NW GP, Inc.<br> General Partner |
| &nbsp;&nbsp;By: | &nbsp;&nbsp;/s/ Aron R. English | &nbsp;&nbsp;/s/ Aron R. English |
|  | &nbsp;&nbsp;Name: | &nbsp;&nbsp;Aron R. English |
|  | &nbsp;&nbsp;Title: | &nbsp;&nbsp;President and Sole Shareholder |

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| | | |
|:---|:---|:---|
| &nbsp;&nbsp;22NW FUND GP, LLC | &nbsp;&nbsp;22NW FUND GP, LLC | &nbsp;&nbsp;22NW FUND GP, LLC |
| &nbsp;&nbsp;By: | &nbsp;&nbsp;/s/ Aron R. English | &nbsp;&nbsp;/s/ Aron R. English |
|  | &nbsp;&nbsp;Name: | &nbsp;&nbsp;Aron R. English |
|  | &nbsp;&nbsp;Title: | &nbsp;&nbsp;Manager |

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| | | |
|:---|:---|:---|
| &nbsp;&nbsp;22NW GP, INC. | &nbsp;&nbsp;22NW GP, INC. | &nbsp;&nbsp;22NW GP, INC. |
| &nbsp;&nbsp;By: | &nbsp;&nbsp;/s/ Aron R. English | &nbsp;&nbsp;/s/ Aron R. English |
|  | &nbsp;&nbsp;Name: | &nbsp;&nbsp;Aron R. English |
|  | &nbsp;&nbsp;Title: | &nbsp;&nbsp;President and Sole Shareholder |

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| |
|:---|
| &nbsp;&nbsp;/s/ Aron R. English |
| &nbsp;&nbsp;ARON R. ENGLISH |

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