Instuitional Investor - Third Rock Ventures, Llc

13F Holdings

Filing Period:

No.	Security	Ticker	Shares	Value	% Port
1.	Sage Therapeutics Inc.	SAGE	11,681,008	$427,525,000	34.96%
2.	Agios Pharmaceuticals Inc.	AGIO	3,070,090	$343,973,000	28.13%
3.	Zafgen Inc.	ZFGN	466,837.08,333,333	$172,767,000	14.12%
4.	Bluebird Bio Inc.	BLUE	93,802.1,688	$111,445,000	9.11%
5.	Foundation Medicine Inc.	FMI	4,927,234	$109,483,000	8.95%