<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
	<head>
		<!-- Document created using Wdesk 1 -->
		<!-- Copyright 2017 Workiva -->
		<title>Document</title>
	</head>
	<body style="font-family:Times New Roman;font-size:10pt;">
<div><a name="s97982B37E55EB2C0152F5B346612F539"></a></div><div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></div><div><br></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">As filed with the Securities and Exchange Commission on August 3, 2017</font></div><div style="line-height:120%;text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Registration No. 333-&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:2pt;">&#160;</font><div style="padding-left:0px;text-indent:0px;line-height:normal;padding-top:10px;"><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman;font-size:10pt;width:100%;border-collapse:collapse;text-align:left;"><tr><td colspan="5"></td></tr><tr><td style="width:21%;"></td><td style="width:19%;"></td><td style="width:19%;"></td><td style="width:19%;"></td><td style="width:22%;"></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:2px solid #000000;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:2px solid #000000;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:2px solid #000000;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:2px solid #000000;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:2px solid #000000;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr></table></div></div><div style="line-height:120%;text-align:center;font-size:17pt;"><font style="font-family:inherit;font-size:17pt;font-weight:bold;">UNITED STATES</font></div><div style="line-height:120%;text-align:center;font-size:17pt;"><font style="font-family:inherit;font-size:17pt;font-weight:bold;">SECURITIES AND EXCHANGE COMMISSION</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">WASHINGTON, D.C. 20549</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">&#160;</font></div><div style="line-height:120%;text-align:center;font-size:17pt;"><font style="font-family:inherit;font-size:17pt;font-weight:bold;">FORM S-8</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">&#160;</font></div><div style="line-height:120%;text-align:center;font-size:11pt;"><font style="font-family:inherit;font-size:11pt;font-weight:bold;">REGISTRATION STATEMENT</font></div><div style="line-height:120%;text-align:center;font-size:11pt;"><font style="font-family:inherit;font-size:11pt;font-weight:bold;">under the</font></div><div style="line-height:120%;text-align:center;font-size:11pt;"><font style="font-family:inherit;font-size:11pt;font-weight:bold;">SECURITIES ACT OF 1933</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">&#160;</font></div><div style="line-height:120%;text-align:center;font-size:17pt;"><font style="font-family:inherit;font-size:17pt;font-weight:bold;">ACCELERON PHARMA INC.</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(Exact name of registrant as specified in its charter)</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;"><br></font></div><div style="line-height:120%;font-size:9pt;"><div style="padding-left:0px;text-indent:0px;line-height:normal;padding-top:10px;"><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman;font-size:10pt;width:99.80506822612085%;border-collapse:collapse;text-align:left;"><tr><td colspan="3"></td></tr><tr><td style="width:48%;"></td><td style="width:4%;"></td><td style="width:48%;"></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Delaware</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(State or other jurisdiction</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">of incorporation or organization)</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;font-weight:bold;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">27-0072226</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(I.R.S. Employer</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Identification No.)</font></div></td></tr></table></div></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;"><br></font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;"><br></font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">128 Sidney Street</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Cambridge, Massachusetts 02139</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">(617) 649-9200</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(Address, including Zip Code, of Principal Executive Offices)</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">&#160;</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;"><br></font></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Acceleron Pharma Inc. 2013 Equity</font><font style="font-family:inherit;font-size:10pt;">&#32;</font><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Incentive Plan</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(Full title of the plan)</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">&#160;</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;"><br></font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Habib J. Dable</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Chief Executive Officer and President</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">128 Sidney Street</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Cambridge, Massachusetts 02139</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">(617) 649-9200</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(Name, address and telephone number, including area code, of agent for service)</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;"><br></font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">with copies to:</font></div><div style="line-height:120%;font-size:9pt;"><div style="padding-left:0px;text-indent:0px;line-height:normal;padding-top:10px;"><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman;font-size:10pt;width:99.80506822612085%;border-collapse:collapse;text-align:left;"><tr><td colspan="3"></td></tr><tr><td style="width:48%;"></td><td style="width:4%;"></td><td style="width:48%;"></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">Marc Rubenstein, Esq.</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Ropes &amp; Gray LLP</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Prudential Tower</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">800 Boylston Street</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Boston, Massachusetts 02199</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(617)&#160;951-7000</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;font-weight:bold;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">John D. Quisel, Ph.D., Esq.</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Senior Vice President, Business Development, General Counsel and Secretary</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Acceleron Pharma Inc.</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">128 Sidney Street</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Cambridge, Massachusetts 02139</font></div><div style="text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(617) 649-9200</font></div></td></tr></table></div></div><div style="line-height:120%;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">&#160;</font></div><div style="line-height:120%;text-indent:36px;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of &#8220;large accelerated filer,&#8221; &#8220;accelerated filer,&#8221; &#8220;smaller reporting company,&#8221; and &#8220;emerging growth company&#8221; in Rule&#160;12b-2 of the Exchange Act.</font></div><div style="line-height:120%;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;"><br></font></div><div style="line-height:120%;font-size:10pt;"><div style="padding-left:0px;text-indent:0px;line-height:normal;padding-top:10px;"><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman;font-size:10pt;width:99.80506822612085%;border-collapse:collapse;text-align:left;"><tr><td colspan="5"></td></tr><tr><td style="width:20%;"></td><td style="width:46%;"></td><td style="width:4%;"></td><td style="width:23%;"></td><td style="width:7%;"></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Large&#160;accelerated&#160;filer</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:Wingdings;font-size:9pt;">x</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Accelerated&#160;filer</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:Wingdings;font-size:9pt;">o</font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td colspan="2" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Non-accelerated filer</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="font-size:9pt;"><font style="font-family:Wingdings;font-size:9pt;">o</font><font style="font-family:inherit;font-size:9pt;">&#160;&#160;(Do not check if a smaller reporting company)</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Smaller&#160;reporting&#160;company</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:Wingdings;font-size:9pt;">o</font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Emerging growth company</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:Wingdings;font-size:9pt;">o</font></div></td></tr></table></div></div><div style="line-height:120%;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;"><br></font></div><div style="line-height:120%;text-indent:36px;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><font style="font-family:Wingdings;font-size:9pt;">o</font></div><div style="line-height:120%;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;"><br></font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;font-weight:bold;">CALCULATION OF REGISTRATION FEE</font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;"><br></font></div><div style="line-height:120%;text-align:center;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;"><br></font></div><div style="line-height:120%;text-align:center;font-size:10pt;"><div style="padding-left:0px;text-indent:0px;line-height:normal;padding-top:10px;"><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman;font-size:10pt;margin-left:auto;margin-right:auto;width:99.80506822612085%;border-collapse:collapse;text-align:left;"><tr><td colspan="17"></td></tr><tr><td style="width:2%;"></td><td style="width:30%;"></td><td style="width:1%;"></td><td style="width:15%;"></td><td style="width:1%;"></td><td style="width:1%;"></td><td style="width:1%;"></td><td style="width:14%;"></td><td style="width:1%;"></td><td style="width:1%;"></td><td style="width:1%;"></td><td style="width:14%;"></td><td style="width:1%;"></td><td style="width:1%;"></td><td style="width:1%;"></td><td style="width:14%;"></td><td style="width:1%;"></td></tr><tr><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:3px double #000000;"><div style="text-align:center;font-size:8pt;"><font style="font-family:inherit;font-size:8pt;font-weight:bold;">Title&#160;of&#160;securities</font></div><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font><font style="font-family:inherit;font-size:8pt;font-weight:bold;">to&#160;be&#160;registered</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:3px double #000000;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:3px double #000000;"><div style="text-align:center;font-size:8pt;"><font style="font-family:inherit;font-size:8pt;font-weight:bold;">Amount&#160;to&#160;be</font></div><div style="text-align:center;font-size:8pt;"><font style="font-family:inherit;font-size:8pt;font-weight:bold;">registered&#160;(1)</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:3px double #000000;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td colspan="3" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:3px double #000000;"><div style="text-align:center;font-size:8pt;"><font style="font-family:inherit;font-size:8pt;font-weight:bold;">Proposed&#160;maximum</font></div><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font><font style="font-family:inherit;font-size:8pt;font-weight:bold;">offering&#160;price</font></div><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font><font style="font-family:inherit;font-size:8pt;font-weight:bold;">per&#160;share (2)</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:3px double #000000;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td colspan="3" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:3px double #000000;"><div style="text-align:center;font-size:8pt;"><font style="font-family:inherit;font-size:8pt;font-weight:bold;">Proposed&#160;maximum</font></div><div style="text-align:center;font-size:8pt;"><font style="font-family:inherit;font-size:8pt;font-weight:bold;">aggregate&#160;offering</font></div><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font><font style="font-family:inherit;font-size:8pt;font-weight:bold;">price (2)</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:3px double #000000;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td colspan="3" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:3px double #000000;"><div style="text-align:center;font-size:8pt;"><font style="font-family:inherit;font-size:8pt;font-weight:bold;">Amount&#160;of</font></div><div style="text-align:center;font-size:8pt;"><font style="font-family:inherit;font-size:8pt;font-weight:bold;">registration&#160;fee</font></div></td></tr><tr><td colspan="2" style="vertical-align:bottom;border-bottom:3px double #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:1px solid #000000;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Common Stock, par value $0.001 per share</font></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">1,530,073</font></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">$</font></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">32.17</font></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">$</font></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">49,222,448.41</font></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">$</font></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;padding-top:2px;padding-bottom:2px;border-top:1px solid #000000;"><div style="text-align:right;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">5,704.88</font></div></td><td style="vertical-align:bottom;border-bottom:3px double #000000;border-top:1px solid #000000;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(1)</font></div></td><td colspan="16" style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">The number of shares of common stock, par value $0.001 per share (&#8220;Common Stock&#8221;), of Acceleron Pharma Inc. (the &#8220;Registrant&#8221;) stated above consists of shares of Common Stock reserved under the Registrant's 2013 Equity Incentive Plan (the &#8220;Plan&#8221;) as a result of the automatic increase in shares reserved thereunder on January&#160;1, 2017 pursuant to the terms of the Plan.  In addition, pursuant to Rule&#160;416 under the Securities Act of 1933, as amended (the &#8220;Securities Act&#8221;), this Registration Statement covers, in addition to the number of shares stated above, an indeterminate number of shares which may be subject to grant or otherwise issuable after the operation of certain&#160;anti-dilution&#160;and other provisions of the Plan.</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">(2)</font></div></td><td colspan="16" style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:9pt;"><font style="font-family:inherit;font-size:9pt;">Pursuant to Rules 457(c) and 457(h) of the Securities Act, the proposed maximum offering price is estimated solely for the purpose of calculating the registration fee and is based on the average of the high and low market prices for the Common Stock reported on the NASDAQ Global Market as of a date (August 1, 2017) within five business days prior to filing this Registration Statement.</font></div></td></tr></table></div></div><div style="line-height:120%;text-align:center;font-size:10pt;"><div style="padding-left:0px;text-indent:0px;line-height:normal;padding-top:10px;"><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman;font-size:10pt;margin-left:auto;margin-right:auto;width:100%;border-collapse:collapse;text-align:left;"><tr><td colspan="5"></td></tr><tr><td style="width:21%;"></td><td style="width:19%;"></td><td style="width:19%;"></td><td style="width:19%;"></td><td style="width:22%;"></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:2px solid #000000;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:2px solid #000000;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:2px solid #000000;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:2px solid #000000;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;border-top:2px solid #000000;"><div style="overflow:hidden;height:5px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr></table></div></div><div><br></div><div></div><hr style="page-break-after:always"><div><a name="s6A78A2947873B7A4E51C5B34664E9E19"></a></div><div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></div><div><br></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">EXPLANATORY NOTE</font></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">This Registration Statement registers additional securities of the same class as other securities for which the registration statement filed on Form S-8 (SEC File No.&#160;333-192789) of the Registrant is effective. The information contained in the Registrant&#8217;s registration statement on Form S-8 (SEC File No.&#160;333-192789) is hereby incorporated by reference pursuant to General Instruction E.</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div><div><a name="sE8D5CB26E13798810B9C5B346666F63D"></a></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">PART&#160;II</font></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">INFORMATION REQUIRED IN THE REGISTRATION STATEMENT</font></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div><div><a name="sCF87A84F3E5CC49809025B3466B691E9"></a></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Item&#160;8. Exhibits.</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">The Exhibits to this Registration Statement are listed in the Exhibit Index immediately following the signature page, which Exhibit Index is incorporated herein by reference.</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div><div><br></div><div style="text-align:center;"><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">2</font></div></div><hr style="page-break-after:always"><div><a name="s2720284F3B3CFAD214895B3466DA78CE"></a></div><div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></div><div><br></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">SIGNATURES</font></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form&#160;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 the 3rd day of August, 2017.</font></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div><div style="line-height:120%;font-size:10pt;"><div style="padding-left:0px;text-indent:0px;line-height:normal;padding-top:10px;"><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman;font-size:10pt;width:99.80506822612085%;border-collapse:collapse;text-align:left;"><tr><td colspan="3"></td></tr><tr><td style="width:49%;"></td><td style="width:6%;"></td><td style="width:45%;"></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td colspan="2" style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">ACCELERON PHARMA INC.</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">By:</font></div></td><td style="vertical-align:top;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">/s/ Habib J. Dable</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Habib J. Dable</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Chief Executive Officer,&#160;President and Director</font></div></td></tr></table></div></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">POWER OF ATTORNEY</font></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Each person whose signature appears below constitutes and appoints Habib J. Dable, Kevin F. McLaughlin and John D. Quisel, Ph.D., Esq., and each of them singly, his true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution in each of them singly, for him and in his name, place and stead, and in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement on Form&#160;S-8 of Acceleron Pharma Inc., and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting to the attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite or necessary to be done in or about the premises, as full to all intents and purposes as he might or could do in person, hereby ratifying and confirming all that the attorneys-in-fact and agents or any of each of them or their substitutes may lawfully do or cause to be done by virtue hereof.</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div><div style="line-height:120%;font-size:10pt;"><div style="padding-left:0px;text-indent:0px;line-height:normal;padding-top:10px;"><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman;font-size:10pt;width:100%;border-collapse:collapse;text-align:left;"><tr><td colspan="5"></td></tr><tr><td style="width:36%;"></td><td style="width:4%;"></td><td style="width:39%;"></td><td style="width:4%;"></td><td style="width:17%;"></td></tr><tr><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:8pt;"><font style="font-family:inherit;font-size:8pt;font-weight:bold;">Signature</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;font-weight:bold;">&#160;</font></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:8pt;"><font style="font-family:inherit;font-size:8pt;font-weight:bold;">Title</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;font-weight:bold;">&#160;</font></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:8pt;"><font style="font-family:inherit;font-size:8pt;font-weight:bold;">Date</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">/s/ Habib J. Dable</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td rowspan="2" style="vertical-align:middle;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Chief Executive Officer, President and Director</font></div><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">(Principal Executive Officer)</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">August 3, 2017</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Habib J. Dable</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">/s/ Kevin F. McLaughlin</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td rowspan="2" style="vertical-align:middle;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Senior Vice President, Chief Financial Officer and Treasurer </font></div><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">(Principal Financial Officer and Principal Accounting Officer)</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">August 3, 2017</font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Kevin F. McLaughlin</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">/s/ Francois Nader, M.D.</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">August 3, 2017</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Francois Nader, M.D.</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Chair of the Board of Directors</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">/s/ Jean M. George</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">August 3, 2017</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Jean M. George</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Director</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">/s/ George Golumbeski, Ph.D.</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">August 3, 2017</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">George Golumbeski, Ph.D.</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Director</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">/s/ Terrence C. Kearney</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">August 3, 2017</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Terrence C. Kearney</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Director</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">/s/ Tom Maniatis, Ph.D.</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">August 3, 2017</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Tom Maniatis, Ph.D.</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Director</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">/s/ Thomas A. McCourt</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">August 3, 2017</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Thomas A. McCourt</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Director</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">/s/ Terrance G. McGuire</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">August 3, 2017</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Terrance G. McGuire</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Director</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">/s/ Richard F. Pops</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">August 3, 2017</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Richard F. Pops</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Director</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">/s/ Joseph S. Zakrzewski</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">August 3, 2017</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Joseph S. Zakrzewski</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Director</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td></tr></table></div></div><div><br></div><div style="text-align:center;"><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">3</font></div></div><hr style="page-break-after:always"><div><a name="s42DC1683DEDD447A68625B34670B3579"></a></div><div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></div><div><br></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">EXHIBIT INDEX</font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div><div style="line-height:120%;font-size:10pt;"><div style="padding-left:0px;text-indent:0px;line-height:normal;padding-top:10px;"><table cellpadding="0" cellspacing="0" style="font-family:Times New Roman;font-size:10pt;width:99.80506822612085%;border-collapse:collapse;text-align:left;"><tr><td colspan="4"></td></tr><tr><td style="width:9%;"></td><td style="width:1%;"></td><td style="width:3%;"></td><td style="width:87%;"></td></tr><tr><td colspan="2" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><font style="font-family:inherit;font-size:8pt;font-weight:bold;">Exhibit</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;font-weight:bold;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;font-weight:bold;">&#160;</font></div></td></tr><tr><td colspan="2" style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:8pt;"><font style="font-family:inherit;font-size:8pt;font-weight:bold;">Number</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;font-weight:bold;">&#160;</font></div></td><td style="vertical-align:bottom;border-bottom:1px solid #000000;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:center;font-size:8pt;"><font style="font-family:inherit;font-size:8pt;font-weight:bold;">Description</font></div></td></tr><tr><td colspan="2" style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">4.1</font></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Restated Certificate of Incorporation of Acceleron Pharma Inc. (previously filed as Exhibit&#160;3.1 to the report on Form&#160;8-K filed September&#160;24, 2013 (File No.&#160;001-36065) and incorporated herein by reference)</font></div></td></tr><tr><td colspan="2" style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">4.2</font></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Amended and Restated Bylaws of Acceleron Pharma Inc. (previously filed as Exhibit&#160;3.2 to the report on Form&#160;8-K filed September&#160;24, 2013 (File No.&#160;001-36065) and incorporated herein by reference)</font></div></td></tr><tr><td colspan="2" style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">4.2.1</font></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Amendment No. 1 to Amended and Restated Bylaws of Acceleron Pharma Inc. (previously filed as Exhibit&#160;3.1 to the report on Form&#160;8-K filed September&#160;12, 2016 (File No.&#160;001-36065) and incorporated herein by reference)</font></div></td></tr><tr><td colspan="2" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">4.3</font></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Form&#160;of Common Stock Certificate, $0.001 par value per share (previously filed as Exhibit&#160;4.1 to the registration statement on Form&#160;S-1 (File No.&#160;333-190417) and incorporated herein by reference)</font></div></td></tr><tr><td colspan="2" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">4.4</font></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Acceleron Pharma Inc. 2013 Equity Incentive Plan (previously filed as Exhibit&#160;4.4 to the registration statement on Form&#160;S-8 (File No.&#160;333-192789) and incorporated herein by reference)</font></div></td></tr><tr><td colspan="2" style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">5.1</font></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Opinion of Ropes&#160;&amp; Gray LLP</font></div></td></tr><tr><td colspan="2" style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="overflow:hidden;height:18px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">23.1</font></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Consent of Ropes&#160;&amp; Gray LLP (included in Exhibit&#160;5.1)</font></div></td></tr><tr><td colspan="2" style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">23.2</font></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Consent of Ernst&#160;&amp; Young LLP</font></div></td></tr><tr><td colspan="2" style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">&#160;</font></div></td></tr><tr><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;"><div style="text-align:right;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">24.1</font></div></td><td style="vertical-align:bottom;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div></td><td style="vertical-align:bottom;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:1pt;"><font style="font-family:inherit;font-size:1pt;">&#160;</font></div></td><td style="vertical-align:top;padding-left:2px;padding-top:2px;padding-bottom:2px;padding-right:2px;"><div style="text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Power of Attorney (included on the signature page&#160;in Part&#160;II)</font></div></td></tr></table></div></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div><div style="line-height:120%;text-align:center;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br></font></div><div><br></div><div style="text-align:center;"><div style="line-height:120%;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">4</font></div></div>	</body>
</html>
[{"type": "S-8", "sequence": "1", "filename": "xlrnforms-82017.htm", "description": "S-8", "secsgml_size_bytes": 100540}]
{"company-data": {"conformed-name": "ACCELERON PHARMA INC", "cik": "0001280600", "assigned-sic": "2836", "irs-number": "000000000", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-219661", "film-number": "171005172"}, "business-address": {"street1": "128 SIDNEY STREET", "city": "CAMBRIDGE", "state": "MA", "zip": "02139", "phone": "617-649-9200"}, "mail-address": {"street1": "128 SIDNEY STREET", "city": "CAMBRIDGE", "state": "MA", "zip": "02139"}}
Document
As filed with the Securities and Exchange Commission on August 3, 2017
Registration No. 333-
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
FORM S-8
REGISTRATION STATEMENT
under the
SECURITIES ACT OF 1933
ACCELERON PHARMA INC.
(Exact name of registrant as specified in its charter)
Delaware
(State or other jurisdiction
of incorporation or organization)
27-0072226
(I.R.S. Employer
Identification No.)
128 Sidney Street
Cambridge, Massachusetts 02139
(617) 649-9200
(Address, including Zip Code, of Principal Executive Offices)
Acceleron Pharma Inc. 2013 Equity
Incentive Plan
(Full title of the plan)
Habib J. Dable
Chief Executive Officer and President
128 Sidney Street
Cambridge, Massachusetts 02139
(617) 649-9200
(Name, address and telephone number, including area code, of agent for service)
with copies to:
Marc Rubenstein, Esq.
Ropes & Gray LLP
Prudential Tower
800 Boylston Street
Boston, Massachusetts 02199
(617) 951-7000
John D. Quisel, Ph.D., Esq.
Senior Vice President, Business Development, General Counsel and Secretary
Acceleron Pharma Inc.
128 Sidney Street
Cambridge, Massachusetts 02139
(617) 649-9200
Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.
Large accelerated filer
x
Accelerated filer
o
Non-accelerated filer
o
(Do not check if a smaller reporting company)
Smaller reporting company
o
Emerging growth company
o
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.
o
CALCULATION OF REGISTRATION FEE
Title of securities
to be registered
Amount to be
registered (1)
Proposed maximum
offering price
per share (2)
Proposed maximum
aggregate offering
price (2)
Amount of
registration fee
Common Stock, par value $0.001 per share
1,530,073
$
32.17
$
49,222,448.41
$
5,704.88
(1)
The number of shares of common stock, par value $0.001 per share ("Common Stock"), of Acceleron Pharma Inc. (the "Registrant") stated above consists of shares of Common Stock reserved under the Registrant's 2013 Equity Incentive Plan (the "Plan") as a result of the automatic increase in shares reserved thereunder on January 1, 2017 pursuant to the terms of the Plan.  In addition, pursuant to Rule 416 under the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement covers, in addition to the number of shares stated above, an indeterminate number of shares which may be subject to grant or otherwise issuable after the operation of certain anti-dilution and other provisions of the Plan.
(2)
Pursuant to Rules 457(c) and 457(h) of the Securities Act, the proposed maximum offering price is estimated solely for the purpose of calculating the registration fee and is based on the average of the high and low market prices for the Common Stock reported on the NASDAQ Global Market as of a date (August 1, 2017) within five business days prior to filing this Registration Statement.
EXPLANATORY NOTE
This Registration Statement registers additional securities of the same class as other securities for which the registration statement filed on Form S-8 (SEC File No. 333-192789) of the Registrant is effective. The information contained in the Registrant's registration statement on Form S-8 (SEC File No. 333-192789) is hereby incorporated by reference pursuant to General Instruction E.
PART II
INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
Item 8. Exhibits.
The Exhibits to this Registration Statement are listed in the Exhibit Index immediately following the signature page, which Exhibit Index is incorporated herein by reference.
2
SIGNATURES
Pursuant to the requirements of the Securities Act of 1933, 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 the 3rd day of August, 2017.
ACCELERON PHARMA INC.
By:
/s/ Habib J. Dable
Habib J. Dable
Chief Executive Officer, President and Director
POWER OF ATTORNEY
Each person whose signature appears below constitutes and appoints Habib J. Dable, Kevin F. McLaughlin and John D. Quisel, Ph.D., Esq., and each of them singly, his true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution in each of them singly, for him and in his name, place and stead, and in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement on Form S-8 of Acceleron Pharma Inc., and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting to the attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite or necessary to be done in or about the premises, as full to all intents and purposes as he might or could do in person, hereby ratifying and confirming all that the attorneys-in-fact and agents or any of each of them or their substitutes may lawfully do or cause to be done by virtue hereof.
Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.
Signature
Title
Date
/s/ Habib J. Dable
Chief Executive Officer, President and Director
(Principal Executive Officer)
August 3, 2017
Habib J. Dable
/s/ Kevin F. McLaughlin
Senior Vice President, Chief Financial Officer and Treasurer
(Principal Financial Officer and Principal Accounting Officer)
August 3, 2017
Kevin F. McLaughlin
/s/ Francois Nader, M.D.
August 3, 2017
Francois Nader, M.D.
Chair of the Board of Directors
/s/ Jean M. George
August 3, 2017
Jean M. George
Director
/s/ George Golumbeski, Ph.D.
August 3, 2017
George Golumbeski, Ph.D.
Director
/s/ Terrence C. Kearney
August 3, 2017
Terrence C. Kearney
Director
/s/ Tom Maniatis, Ph.D.
August 3, 2017
Tom Maniatis, Ph.D.
Director
/s/ Thomas A. McCourt
August 3, 2017
Thomas A. McCourt
Director
/s/ Terrance G. McGuire
August 3, 2017
Terrance G. McGuire
Director
/s/ Richard F. Pops
August 3, 2017
Richard F. Pops
Director
/s/ Joseph S. Zakrzewski
August 3, 2017
Joseph S. Zakrzewski
Director
3
EXHIBIT INDEX
Exhibit
Number
Description
4.1
Restated Certificate of Incorporation of Acceleron Pharma Inc. (previously filed as Exhibit 3.1 to the report on Form 8-K filed September 24, 2013 (File No. 001-36065) and incorporated herein by reference)
4.2
Amended and Restated Bylaws of Acceleron Pharma Inc. (previously filed as Exhibit 3.2 to the report on Form 8-K filed September 24, 2013 (File No. 001-36065) and incorporated herein by reference)
4.2.1
Amendment No. 1 to Amended and Restated Bylaws of Acceleron Pharma Inc. (previously filed as Exhibit 3.1 to the report on Form 8-K filed September 12, 2016 (File No. 001-36065) and incorporated herein by reference)
4.3
Form of Common Stock Certificate, $0.001 par value per share (previously filed as Exhibit 4.1 to the registration statement on Form S-1 (File No. 333-190417) and incorporated herein by reference)
4.4
Acceleron Pharma Inc. 2013 Equity Incentive Plan (previously filed as Exhibit 4.4 to the registration statement on Form S-8 (File No. 333-192789) and incorporated herein by reference)
5.1
Opinion of Ropes & Gray LLP
23.1
Consent of Ropes & Gray LLP (included in Exhibit 5.1)
23.2
Consent of Ernst & Young LLP
24.1
Power of Attorney (included on the signature page in Part II)
4