<html>
<head>

  </head>
<body lang="EN-US">
<div style="font-family:Times New Roman;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">As filed with the Securities and Exchange Commission on February 1, 2013</font></b></p>
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Registration No. 333-&#160;&#160;&#160;&#160;&#160; </font></b></p>
<div style="border-bottom:solid windowtext 1.0pt;border-left:none;border-right:none;border-top:solid windowtext 3.0pt;padding:1.0pt 0in 1.0pt 0in;">
<p style="border:none;margin:0in 0in .0001pt;padding:0in;"><font size="1" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
</div>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;">UNITED STATES<br> SECURITIES AND EXCHANGE COMMISSION</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">WASHINGTON, DC 20549</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;">FORM S-8</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">REGISTRATION STATEMENT UNDER<br> THE SECURITIES ACT OF 1933</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;">MERRIMACK PHARMACEUTICALS, INC.</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Exact Name of Registrant as Specified in Its Charter)</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<div align="center">
<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
<tr>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Delaware</font></b></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">04-3210530</font></b></p>    </td>   </tr>
<tr>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(State or Other Jurisdiction of Incorporation</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">or Organization)</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(I.R.S. Employer<br>   Identification No.)</font></p>    </td>   </tr>
<tr>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">One Kendall Square, Suite B7201</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Cambridge, MA</font></b></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
<p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>
<td width="49%" valign="bottom" style="padding:0in 0in 0in 0in;width:49.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">02139</font></b></p>    </td>   </tr>
<tr>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Address of Principal Executive Offices)</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Zip Code)</font></p>    </td>   </tr>  </table>
</div>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">2011 Stock Incentive Plan</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Full Title of the Plan)</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Robert J. Mulroy</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">President and Chief Executive Officer</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Merrimack Pharmaceuticals, Inc.</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">One Kendall Square, Suite B7201</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Cambridge, Massachusetts 02139</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Name and Address of Agent for Service)</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(617) 441-1000</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Telephone Number, Including Area Code, of Agent For Service)</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of &#147;large accelerated filer,&#148; &#147;accelerated filer&#148; and &#147;smaller reporting company&#148; in Rule 12b of the Exchange Act.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<div align="center">
<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
<tr>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p style="margin:0in 0in .0001pt .5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Large accelerated filer </font><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p style="margin:0in 0in .0001pt 54.2pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Accelerated filer </font><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font></p>    </td>   </tr>
<tr>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p style="margin:0in 0in .0001pt .5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p style="margin:0in 0in .0001pt 54.2pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p style="margin:0in 0in .0001pt .5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Non-accelerated filer </font><font size="2" face="Wingdings" style="font-size:10.0pt;">x</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p style="margin:0in 0in .0001pt 54.2pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Smaller reporting company </font><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font></p>    </td>   </tr>
<tr>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Do not check if a smaller reporting company)</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="49%" valign="top" style="padding:0in 0in 0in 0in;width:49.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>  </table>
</div>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">CALCULATION OF REGISTRATION FEE</font></b></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
<tr>
<td width="31%" valign="bottom" style="border-bottom:solid windowtext 1.0pt;border-left:none;border-right:none;border-top:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:31.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Title of<br>   Securities to be<br>   Registered</font></b></p>    </td>
<td width="2%" valign="bottom" style="border-bottom:solid windowtext 1.0pt;border-left:none;border-right:none;border-top:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:2.5%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>
<td width="14%" valign="bottom" style="border-bottom:solid windowtext 1.0pt;border-left:none;border-right:none;border-top:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:14.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Amount to be<br>   Registered(1)</font></b></p>    </td>
<td width="2%" valign="bottom" style="border-bottom:solid windowtext 1.0pt;border-left:none;border-right:none;border-top:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:2.5%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>
<td width="14%" colspan="2" valign="bottom" style="border-bottom:solid windowtext 1.0pt;border-left:none;border-right:none;border-top:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:14.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Proposed<br>   Maximum<br>   Offering Price Per<br>   Share</font></b></p>    </td>
<td width="3%" valign="bottom" style="border-bottom:solid windowtext 1.0pt;border-left:none;border-right:none;border-top:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:3.5%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>
<td width="14%" colspan="2" valign="bottom" style="border-bottom:solid windowtext 1.0pt;border-left:none;border-right:none;border-top:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:14.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Proposed<br>   Maximum<br>   Aggregate<br>   Offering Price</font></b></p>    </td>
<td width="3%" valign="bottom" style="border-bottom:solid windowtext 1.0pt;border-left:none;border-right:none;border-top:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:3.5%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>
<td width="14%" colspan="2" valign="bottom" style="border-bottom:solid windowtext 1.0pt;border-left:none;border-right:none;border-top:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:14.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Amount of<br>   Registration Fee</font></b></p>    </td>
<td width="1%" valign="bottom" style="border-bottom:solid windowtext 1.0pt;border-left:none;border-right:none;border-top:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:1.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>   </tr>
<tr>
<td width="31%" valign="top" style="border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:31.0%;">
<p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Common Stock, $0.01 par value per share </font></p>    </td>
<td width="2%" valign="bottom" style="border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:2.5%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="14%" valign="bottom" style="border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:14.0%;">
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">3,353,882 shares</font></p>    </td>
<td width="2%" valign="bottom" style="border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:2.5%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="1%" valign="bottom" style="border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:1.3%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">$</font></p>    </td>
<td width="12%" valign="bottom" style="border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:12.7%;">
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">6.125</font></p>    </td>
<td width="3%" valign="bottom" style="border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:3.5%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(2)</font></p>    </td>
<td width="1%" valign="bottom" style="border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:1.3%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">$</font></p>    </td>
<td width="12%" valign="bottom" style="border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:12.7%;">
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">20,542,527.25</font></p>    </td>
<td width="3%" valign="bottom" style="border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:3.5%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(2)</font></p>    </td>
<td width="1%" valign="bottom" style="border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:1.3%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">$</font></p>    </td>
<td width="12%" valign="bottom" style="border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:12.7%;">
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2,802.01</font></p>    </td>
<td width="1%" valign="bottom" style="border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:1.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr height="0">
<td width="232" style="border:none;"></td>
<td width="19" style="border:none;"></td>
<td width="105" style="border:none;"></td>
<td width="19" style="border:none;"></td>
<td width="10" style="border:none;"></td>
<td width="95" style="border:none;"></td>
<td width="26" style="border:none;"></td>
<td width="10" style="border:none;"></td>
<td width="95" style="border:none;"></td>
<td width="26" style="border:none;"></td>
<td width="10" style="border:none;"></td>
<td width="95" style="border:none;"></td>
<td width="7" style="border:none;"></td>   </tr> </table>
<p style="margin:0in 0in .0001pt .5in;text-indent:-.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(1)</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><font size="2" style="font-size:10.0pt;">In accordance with Rule 416 under the Securities Act of 1933, as amended, this registration statement shall be deemed to cover any additional securities that may from time to time be offered or issued to prevent dilution resulting from stock splits, stock dividends or similar transactions.</font></p>
<p style="margin:0in 0in .0001pt .5in;text-indent:-.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt .5in;text-indent:-33.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(2)</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><font size="2" style="font-size:10.0pt;">Estimated solely for the purpose of calculating the registration fee pursuant to Rules 457(c) and 457(h) of the Securities Act of 1933, as amended, and based upon the average of the high and low prices of the Registrant&#146;s Common Stock as reported on the NASDAQ Global Market on January 28, 2013.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<div style="border-bottom:solid windowtext 3.0pt;border-left:none;border-right:none;border-top:solid windowtext 1.0pt;padding:1.0pt 0in 1.0pt 0in;">
<p style="border:none;margin:0in 0in .0001pt;padding:0in;"><font size="1" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
</div>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>
</div>
<!-- SEQ.=1,FOLIO='',FILE='C:\JMS\107594\13-3947-1\task5774777\3947-1-ba.htm',USER='107594',CD='Jan 31 23:01 2013' -->


<br clear="all" style="page-break-before:always;">
<div>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">EXPLANATORY NOTE</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">This Registration Statement on Form S-8, relating to the 2011 Stock Incentive Plan of Merrimack Pharmaceuticals, Inc. (the &#147;Registrant&#148;), is being filed for the purpose of registering additional securities of the same class as other securities for which a Registration Statement on Form S-8 has previously been filed and is effective.&#160; Accordingly, this Registration Statement incorporates by reference the contents of the Registration Statement on Form S-8, File No. 333-180996, filed with the Securities and Exchange Commission on April 27, 2012 by the Registrant, relating to the Registrant&#146;s 1999 Stock Option Plan, as amended, 2008 Stock Incentive Plan, as amended, and 2011 Stock Incentive Plan, except for Item 8, Exhibits, with respect to which the Exhibit Index immediately preceding the exhibits attached hereto is incorporated herein by reference.</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">1<a name="PB_1_222048_7056"></a></font></p>
<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>
</div>
<!-- SEQ.=1,FOLIO='1',FILE='C:\JMS\107594\13-3947-1\task5774777\3947-1-bc.htm',USER='107594',CD='Jan 31 23:01 2013' -->

<br clear="all" style="page-break-before:always;">
<div style="font-family:Times New Roman;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">SIGNATURES</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Cambridge, Commonwealth of Massachusetts, on this 1</font><font size="1" style="font-size:6.5pt;position:relative;top:-3.0pt;">st</font><font size="2" style="font-size:10.0pt;">&#160;day of February, 2013.</font></p>
<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
<tr>
<td width="50%" valign="top" style="padding:0in 0in 0in 0in;width:50.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="49%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:49.58%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">MERRIMACK   PHARMACEUTICALS, INC.</font></p>    </td>   </tr>
<tr>
<td width="50%" valign="top" style="padding:0in 0in 0in 0in;width:50.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="49%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:49.58%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="50%" valign="top" style="padding:0in 0in 0in 0in;width:50.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="49%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:49.58%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="50%" valign="top" style="padding:0in 0in 0in 0in;width:50.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="4%" valign="top" style="padding:0in 0in 0in 0in;width:4.16%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:</font></p>    </td>
<td width="45%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:45.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/   Robert J. Mulroy</font></p>    </td>   </tr>
<tr>
<td width="50%" valign="top" style="padding:0in 0in 0in 0in;width:50.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="4%" valign="top" style="padding:0in 0in 0in 0in;width:4.16%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="45%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:45.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Robert   J. Mulroy</font></p>    </td>   </tr>
<tr>
<td width="50%" valign="top" style="padding:0in 0in 0in 0in;width:50.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="4%" valign="top" style="padding:0in 0in 0in 0in;width:4.16%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="45%" valign="top" style="padding:0in 0in 0in 0in;width:45.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">President   and Chief Executive Officer</font></p>    </td>   </tr>  </table>
<p style="margin:0in 0in .0001pt 3.0in;text-indent:22.5pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">POWER OF ATTORNEY AND SIGNATURES</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">We, the undersigned officers and directors of Merrimack Pharmaceuticals, Inc., hereby severally constitute and appoint Robert J. Mulroy and William A. Sullivan, and each of them singly, our true and lawful attorneys with full power to any of them, and to each of them singly, to sign for us and in our names in the capacities indicated below the Registration Statement on Form S-8 filed herewith and any and all amendments to said Registration Statement, and generally to do all such things in our name and on our behalf in our capacities as officers and directors to enable Merrimack Pharmaceuticals, Inc. to comply with the provisions of the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission, hereby ratifying and confirming our signatures as they may be signed by our said attorneys, or any of them, to said registration statement and any and all amendments thereto.</font></p>
<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
<tr>
<td width="29%" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:29.84%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Signature</font></b></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.86%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>
<td width="43%" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:43.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Title</font></b></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.92%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>
<td width="21%" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:21.38%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Date</font></b></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/   Robert J. Mulroy</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">President,   Chief Executive Officer and Director</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February   1, 2013</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Robert   J. Mulroy</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Principal   Executive Officer)</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/   William A. Sullivan</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Chief   Financial Officer and Treasurer</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February   1, 2013</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">William   A. Sullivan</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Principal   Financial and Accounting Officer)</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/   Gary L. Crocker</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Chairman   of the Board</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February   1, 2013</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Gary   L. Crocker</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/   James van B. Dresser</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Director</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February   1, 2013</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">James   van B. Dresser</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/   Gordon J. Fehr</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Director</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February   1, 2013</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Gordon   J. Fehr</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/   John Mendelsohn, M.D.</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Director</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February   1, 2013</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">John   Mendelsohn, M.D.</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>  </table>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2<a name="PB_2_195913_2897"></a></font></p>
<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>
</div>
<!-- SEQ.=1,FOLIO='2',FILE='C:\JMS\107594\13-3947-1\task5774777\3947-1-bc.htm',USER='107594',CD='Jan 31 23:01 2013' -->

<br clear="all" style="page-break-before:always;">
<div>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
<tr>
<td width="29%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/   Sarah E. Nash</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Director</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February   1, 2013</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Sarah   E. Nash</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/   Michael E. Porter, Ph.D.</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Director</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February   1, 2013</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Michael   E. Porter, Ph.D.</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/   James H. Quigley</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Director</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February   1, 2013</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">James   H. Quigley</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/   Anthony J. Sinskey, Sc.D.</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Director</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February   1, 2013</font></p>    </td>   </tr>
<tr>
<td width="29%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:29.84%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Anthony   J. Sinskey, Sc.D.</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.86%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.92%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="21%" valign="top" style="padding:0in 0in 0in 0in;width:21.38%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>   </tr>  </table>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">3<a name="PB_3_195918_3020"></a></font></p>
<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>
</div>
<!-- SEQ.=1,FOLIO='3',FILE='C:\JMS\107594\13-3947-1\task5774777\3947-1-bc.htm',USER='107594',CD='Jan 31 23:01 2013' -->

<br clear="all" style="page-break-before:always;">
<div style="font-family:Times New Roman;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">EXHIBIT INDEX</font></b></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
<tr>
<td width="8%" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:8.7%;">
<p style="margin:0in 0in .0001pt;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Exhibit   No.</font></b></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.3%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>
<td width="89%" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:89.0%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Description</font></b></p>    </td>   </tr>
<tr>
<td width="8%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:8.7%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.3%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="89%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:89.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="8%" valign="top" style="padding:0in 0in 0in 0in;width:8.7%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">4.1(1)</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.3%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="89%" valign="top" style="padding:0in 0in 0in 0in;width:89.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Restated   Certificate of Incorporation of the Registrant</font></p>    </td>   </tr>
<tr>
<td width="8%" valign="top" style="padding:0in 0in 0in 0in;width:8.7%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">4.2(2)</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.3%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="89%" valign="top" style="padding:0in 0in 0in 0in;width:89.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Amended   and Restated Bylaws of the Registrant</font></p>    </td>   </tr>
<tr>
<td width="8%" valign="top" style="padding:0in 0in 0in 0in;width:8.7%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">5.1</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.3%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="89%" valign="top" style="padding:0in 0in 0in 0in;width:89.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Opinion   of Wilmer Cutler Pickering Hale and Dorr LLP</font></p>    </td>   </tr>
<tr>
<td width="8%" valign="top" style="padding:0in 0in 0in 0in;width:8.7%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">23.1</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.3%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="89%" valign="top" style="padding:0in 0in 0in 0in;width:89.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Consent   of Wilmer Cutler Pickering Hale and Dorr LLP, counsel to the Registrant   (included in Exhibit 5.1)</font></p>    </td>   </tr>
<tr>
<td width="8%" valign="top" style="padding:0in 0in 0in 0in;width:8.7%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">23.2</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.3%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="89%" valign="top" style="padding:0in 0in 0in 0in;width:89.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Consent   of PricewaterhouseCoopers LLP, independent registered public accounting firm   for the Registrant</font></p>    </td>   </tr>
<tr>
<td width="8%" valign="top" style="padding:0in 0in 0in 0in;width:8.7%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">24.1</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.3%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="89%" valign="top" style="padding:0in 0in 0in 0in;width:89.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Powers   of Attorney (included on the signature pages to the Registration Statement)</font></p>    </td>   </tr>
<tr>
<td width="8%" valign="top" style="padding:0in 0in 0in 0in;width:8.7%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">99.1(2)</font></p>    </td>
<td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.3%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="89%" valign="top" style="padding:0in 0in 0in 0in;width:89.0%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2011   Stock Incentive Plan</font></p>    </td>   </tr>  </table>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<div style="margin:0in 0in .0001pt;"><hr size="1" width="25%" noshade color="black" align="left"></div>
<p style="margin:0in 0in .0001pt .5in;text-indent:-.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(1)</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><font size="2" style="font-size:10.0pt;">Previously filed with the Securities and Exchange Commission as an Exhibit to the Registrant&#146;s Registration Statement on Form S-8 (File No. 333-180996) and incorporated herein by reference.</font></p>
<p style="margin:0in 0in .0001pt .5in;text-indent:-.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt .5in;text-indent:-.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(2)</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><font size="2" style="font-size:10.0pt;">Previously filed with the Securities and Exchange Commission as an Exhibit to the Registrant&#146;s Registration Statement on Form S-1, as amended (File No. 333-175427), and incorporated herein by reference.</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">4<a name="PB_4_195928_7748"></a></font></p>
<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>
</div>
<!-- SEQ.=1,FOLIO='4',FILE='C:\JMS\107594\13-3947-1\task5774777\3947-1-bc.htm',USER='107594',CD='Jan 31 23:01 2013' -->

</body>
</html>
[{"type": "S-8", "sequence": "1", "filename": "a13-3947_1s8.htm", "description": "S-8", "secsgml_size_bytes": 75941}]
{"company-data": {"conformed-name": "MERRIMACK PHARMACEUTICALS INC", "cik": "0001274792", "assigned-sic": "2834", "irs-number": "000000000", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-186370", "film-number": "13565224"}, "business-address": {"street1": "ONE KENDALL SQUARE", "street2": "SUITE B7201", "city": "CAMBRIDGE", "state": "MA", "zip": "02139", "phone": "617-441-1000"}, "mail-address": {"street1": "ONE KENDALL SQUARE", "street2": "SUITE B7201", "city": "CAMBRIDGE", "state": "MA", "zip": "02139"}}
As filed with the Securities and Exchange Commission on February 1, 2013
Registration No. 333-
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, DC 20549
FORM S-8
REGISTRATION STATEMENT UNDER
THE SECURITIES ACT OF 1933
MERRIMACK PHARMACEUTICALS, INC.
(Exact Name of Registrant as Specified in Its Charter)
Delaware
04-3210530
(State or Other Jurisdiction of Incorporation
or Organization)
(I.R.S. Employer
Identification No.)
One Kendall Square, Suite B7201
Cambridge, MA
02139
(Address of Principal Executive Offices)
(Zip Code)
2011 Stock Incentive Plan
(Full Title of the Plan)
Robert J. Mulroy
President and Chief Executive Officer
Merrimack Pharmaceuticals, Inc.
One Kendall Square, Suite B7201
Cambridge, Massachusetts 02139
(Name and Address of Agent for Service)
(617) 441-1000
(Telephone Number, Including Area Code, of Agent For Service)
Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of "large accelerated filer," "accelerated filer" and "smaller reporting company" in Rule 12b of the Exchange Act.
Large accelerated filer
o
Accelerated filer
o
Non-accelerated filer
x
Smaller reporting company
o
(Do not check if a smaller reporting company)
CALCULATION OF REGISTRATION FEE
Title of
Securities to be
Registered
Amount to be
Registered(1)
Proposed
Maximum
Offering Price Per
Share
Proposed
Maximum
Aggregate
Offering Price
Amount of
Registration Fee
Common Stock, $0.01 par value per share
3,353,882 shares
$
6.125
(2)
$
20,542,527.25
(2)
$
2,802.01
(1)
In accordance with Rule 416 under the Securities Act of 1933, as amended, this registration statement shall be deemed to cover any additional securities that may from time to time be offered or issued to prevent dilution resulting from stock splits, stock dividends or similar transactions.
(2)
Estimated solely for the purpose of calculating the registration fee pursuant to Rules 457(c) and 457(h) of the Securities Act of 1933, as amended, and based upon the average of the high and low prices of the Registrant's Common Stock as reported on the NASDAQ Global Market on January 28, 2013.
EXPLANATORY NOTE
This Registration Statement on Form S-8, relating to the 2011 Stock Incentive Plan of Merrimack Pharmaceuticals, Inc. (the "Registrant"), is being filed for the purpose of registering additional securities of the same class as other securities for which a Registration Statement on Form S-8 has previously been filed and is effective.  Accordingly, this Registration Statement incorporates by reference the contents of the Registration Statement on Form S-8, File No. 333-180996, filed with the Securities and Exchange Commission on April 27, 2012 by the Registrant, relating to the Registrant's 1999 Stock Option Plan, as amended, 2008 Stock Incentive Plan, as amended, and 2011 Stock Incentive Plan, except for Item 8, Exhibits, with respect to which the Exhibit Index immediately preceding the exhibits attached hereto is incorporated herein by reference.
1
SIGNATURES
Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Cambridge, Commonwealth of Massachusetts, on this 1
st
day of February, 2013.
MERRIMACK   PHARMACEUTICALS, INC.
By:
/s/   Robert J. Mulroy
Robert   J. Mulroy
President   and Chief Executive Officer
POWER OF ATTORNEY AND SIGNATURES
We, the undersigned officers and directors of Merrimack Pharmaceuticals, Inc., hereby severally constitute and appoint Robert J. Mulroy and William A. Sullivan, and each of them singly, our true and lawful attorneys with full power to any of them, and to each of them singly, to sign for us and in our names in the capacities indicated below the Registration Statement on Form S-8 filed herewith and any and all amendments to said Registration Statement, and generally to do all such things in our name and on our behalf in our capacities as officers and directors to enable Merrimack Pharmaceuticals, Inc. to comply with the provisions of the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission, hereby ratifying and confirming our signatures as they may be signed by our said attorneys, or any of them, to said registration statement and any and all amendments thereto.
Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.
Signature
Title
Date
/s/   Robert J. Mulroy
President,   Chief Executive Officer and Director
February   1, 2013
Robert   J. Mulroy
(Principal   Executive Officer)
/s/   William A. Sullivan
Chief   Financial Officer and Treasurer
February   1, 2013
William   A. Sullivan
(Principal   Financial and Accounting Officer)
/s/   Gary L. Crocker
Chairman   of the Board
February   1, 2013
Gary   L. Crocker
/s/   James van B. Dresser
Director
February   1, 2013
James   van B. Dresser
/s/   Gordon J. Fehr
Director
February   1, 2013
Gordon   J. Fehr
/s/   John Mendelsohn, M.D.
Director
February   1, 2013
John   Mendelsohn, M.D.
2
/s/   Sarah E. Nash
Director
February   1, 2013
Sarah   E. Nash
/s/   Michael E. Porter, Ph.D.
Director
February   1, 2013
Michael   E. Porter, Ph.D.
/s/   James H. Quigley
Director
February   1, 2013
James   H. Quigley
/s/   Anthony J. Sinskey, Sc.D.
Director
February   1, 2013
Anthony   J. Sinskey, Sc.D.
3
EXHIBIT INDEX
Exhibit   No.
Description
4.1(1)
Restated   Certificate of Incorporation of the Registrant
4.2(2)
Amended   and Restated Bylaws of the Registrant
5.1
Opinion   of Wilmer Cutler Pickering Hale and Dorr LLP
23.1
Consent   of Wilmer Cutler Pickering Hale and Dorr LLP, counsel to the Registrant   (included in Exhibit 5.1)
23.2
Consent   of PricewaterhouseCoopers LLP, independent registered public accounting firm   for the Registrant
24.1
Powers   of Attorney (included on the signature pages to the Registration Statement)
99.1(2)
2011   Stock Incentive Plan
(1)
Previously filed with the Securities and Exchange Commission as an Exhibit to the Registrant's Registration Statement on Form S-8 (File No. 333-180996) and incorporated herein by reference.
(2)
Previously filed with the Securities and Exchange Commission as an Exhibit to the Registrant's Registration Statement on Form S-1, as amended (File No. 333-175427), and incorporated herein by reference.
4