Consolidated Subsidiaries	12 Months Ended
Dec. 31, 2013
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Consolidated Subsidiaries	7. Consolidated Subsidiaries Hermes BioSciences, Inc. On October 6, 2009, (the “Acquisition Date”), the Company completed the acquisition of all outstanding shares of Hermes, a privately-held biotechnology company developing lipidic nano-carriers to allow for targeted delivery of small molecule drugs, including chemotherapies, with the goal of improving cancer treatment safety and efficacy. Silver Creek Pharmaceuticals, Inc. On August 20, 2010, the Company acquired a controlling interest in Silver Creek. In December 2012, as described in Note 11, “Borrowings,” Silver Creek entered into a Note Purchase Agreement pursuant to which it issued convertible notes to various lenders in aggregate principal amounts of $1.6 million in December 2012, $0.3 million in February 2013 and $0.6 million in December 2013. As of December 31, 2013, Silver Creek’s outstanding borrowings and related accrued interest of $2.6 million converted to shares of Silver Creek Series A preferred stock at the Series A preferred stock value of $1.00 per share. As a result of changes to the ownership composition of Silver Creek, the non-controlling interest increased by $0.8 million. As of December 31, 2013 and 2012, the Company owned 64% and 74% of the voting stock of Silver Creek, respectively, and recorded a non-controlling interest of $337,000 and $97,000, respectively, as a component of mezzanine equity on the Company’s consolidated balance sheets based on the terms of the Silver Creek Series A preferred stock. As of December 31, 2013, the Company consolidated Silver Creek’s total assets and total liabilities of $1.0 million and $0.1 million, respectively. As of December 31, 2012, the Company consolidated Silver Creek’s total assets and total liabilities of $2.2 million and $1.8 million, respectively. As of December 31, 2013 and 2012, employees and directors of the Company owned approximately 7% and 6% of the outstanding shares of Silver Creek Series A preferred stock, respectively. Merrimack Pharmaceuticals (Bermuda) Ltd. Merrimack Pharmaceuticals (Bermuda) Ltd. was incorporated in Bermuda during 2011, is wholly owned by the Company and holds certain intellectual property rights with respect to MM-398.

7. Consolidated Subsidiaries

Hermes BioSciences, Inc.

On October 6, 2009, (the “Acquisition Date”), the Company completed the acquisition of all outstanding shares of Hermes, a privately-held biotechnology company developing lipidic nano-carriers to allow for targeted delivery of small molecule drugs, including chemotherapies, with the goal of improving cancer treatment safety and efficacy.

Silver Creek Pharmaceuticals, Inc.

On August 20, 2010, the Company acquired a controlling interest in Silver Creek. In December 2012, as described in Note 11, “Borrowings,” Silver Creek entered into a Note Purchase Agreement pursuant to which it issued convertible notes to various lenders in aggregate principal amounts of $1.6 million in December 2012, $0.3 million in February 2013 and $0.6 million in December 2013. As of December 31, 2013, Silver Creek’s outstanding borrowings and related accrued interest of $2.6 million converted to shares of Silver Creek Series A preferred stock at the Series A preferred stock value of $1.00 per share. As a result of changes to the ownership composition of Silver Creek, the non-controlling interest increased by $0.8 million. As of December 31, 2013 and 2012, the Company owned 64% and 74% of the voting stock of Silver Creek, respectively, and recorded a non-controlling interest of $337,000 and $97,000, respectively, as a component of mezzanine equity on the Company’s consolidated balance sheets based on the terms of the Silver Creek Series A preferred stock.

As of December 31, 2013, the Company consolidated Silver Creek’s total assets and total liabilities of $1.0 million and $0.1 million, respectively. As of December 31, 2012, the Company consolidated Silver Creek’s total assets and total liabilities of $2.2 million and $1.8 million, respectively.

As of December 31, 2013 and 2012, employees and directors of the Company owned approximately 7% and 6% of the outstanding shares of Silver Creek Series A preferred stock, respectively.

Merrimack Pharmaceuticals (Bermuda) Ltd.

Merrimack Pharmaceuticals (Bermuda) Ltd. was incorporated in Bermuda during 2011, is wholly owned by the Company and holds certain intellectual property rights with respect to MM-398.