Item 7.01.  Regulation FD Disclosure.

Merrimack Pharmaceuticals, Inc. (the “Company”) from time to time presents and/or distributes to the investment community at various industry and other conferences slide presentations to provide updates and summaries of its business. The Company is posting to the Investors portion of its website at investors.merrimackpharma.com copies of its current corporate slide presentation and factsheet. These slides are attached to this Current Report on Form 8-K as Exhibit 99.1 and Exhibit 99.2. The Company undertakes no obligation to update, supplement or amend the materials attached hereto as Exhibit 99.1 or Exhibit 99.2.

In accordance with General Instruction B.2 of Form 8-K, the information in this Item 7.01 of this Current Report on Form 8-K, including Exhibit 99.1 and Exhibit 99.2, shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Exchange Act or the Securities Act of 1933, as amended, except as shall be expressly set forth by reference in such a filing.

Item 9.01.  Financial Statements and Exhibits.

(d)  Exhibits.

See Exhibit Index attached hereto.

Forward Looking Statements

The attached exhibits contain forward-looking statements that involve substantial risks and uncertainties.  All statements, other than statements of historical facts, contained in these exhibits, including statements regarding our strategy, future operations, future financial position, future revenues, projected costs, prospects, plans and objectives of management, are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended.  The words “anticipate,” “believe,” “estimate,” “expect,” “intend,” “may,” “plan,” “predict,” “project,” “target,” “potential,” “will,” “would,” “could,” “should,” “continue” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.  We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements.  Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make.  These forward-looking statements include, among other things, statements about: our plans to develop and commercialize our most advanced product candidates and companion diagnostics; our ongoing and planned discovery programs, preclinical studies and clinical trials; our anticipated milestones; adequacy of funding for Merrimack’s foreseeable and unforeseeable operating expenses and capital expenditure requirements; and the success or consummation of potential business development activities.  For more information regarding important factors that we believe could cause actual results or events to differ materially from the forward-looking statements that we make, see the “Risk Factors” section of our Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission, or SEC, on August 8, 2013 and other reports we file with the SEC.  Any forward-looking statement contained in these exhibits reflects Merrimack’s views as of the date of the document with respect to future events and Merrimack assumes no obligation to publicly update or revise these forward-looking statements for any reason, or to update the reasons actual results could differ materially from those anticipated in these forward-looking statements, even if new information becomes available in the future, except as otherwise required by applicable law.

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SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

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EXHIBIT INDEX

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