Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2012

Selected Quarterly Financial Data (Unaudited)

Schedule of quarterly financial information

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	(in thousands, except per share data)
2011
Collaboration revenues	$	6,461		$	6,595		$	8,582		$	12,577
Total operating expenses		21,102			36,019			27,219			30,744
Net loss		(13,535	)		(29,196	)		(18,724	)		(18,221	)
Net loss attributable to Merrimack Pharmaceuticals, Inc.		(13,457	)		(29,051	)		(18,599	)		(18,116	)
Net loss per share available to common stockholders—basic and diluted	$	(1.34	)	$	(2.76	)	$	(1.81	)	$	(1.76	)

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	(in thousands, except per share data)
2012
Collaboration revenues	$	11,344		$	12,063		$	11,323		$	14,191
Total operating expenses		35,379			32,368			35,197			38,719
Net loss		(23,402	)		(20,139	)		(23,320	)		(24,893	)
Net loss attributable to Merrimack Pharmaceuticals, Inc.		(23,284	)		(20,026	)		(23,199	)		(24,768	)
Net loss per share available to common stockholders—basic and diluted	$	(2.14	)	$	(0.22	)	$	(0.25	)	$	(0.26	)