<SEC-DOCUMENT>0001839882-21-002169-index.html : 20210216
<SEC-HEADER>0001839882-21-002169.hdr.sgml : 20210216
<ACCEPTANCE-DATETIME>20210216172819
ACCESSION NUMBER:		0001839882-21-002169
CONFORMED SUBMISSION TYPE:	SC 13G
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20210216
DATE AS OF CHANGE:		20210216
GROUP MEMBERS:		ATLAS VENTURE ASSOCIATES OPPORTUNITY I, L.P.
GROUP MEMBERS:		ATLAS VENTURE ASSOCIATES OPPORTUNITY I, LLC
GROUP MEMBERS:		ATLAS VENTURE ASSOCIATES X, L.P.
GROUP MEMBERS:		ATLAS VENTURE ASSOCIATES X, LLC
GROUP MEMBERS:		ATLAS VENTURE OPPORTUNITY FUND I, L.P.

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Generation Bio Co.
		CENTRAL INDEX KEY:			0001733294
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				814301281
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13G
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-91530
		FILM NUMBER:		21641090

	BUSINESS ADDRESS:	
		STREET 1:		301 BINNEY STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142
		BUSINESS PHONE:		857-529-5908

	MAIL ADDRESS:	
		STREET 1:		301 BINNEY STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142

FILED BY:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Atlas Venture Fund X, L.P.
		CENTRAL INDEX KEY:			0001628098
		IRS NUMBER:				472435989
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13G

	BUSINESS ADDRESS:	
		STREET 1:		400 TECHNOLOGY SQUARE
		STREET 2:		10TH FLOOR
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
		BUSINESS PHONE:		857-201-2700

	MAIL ADDRESS:	
		STREET 1:		400 TECHNOLOGY SQUARE
		STREET 2:		10TH FLOOR
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
</SEC-HEADER>
<DOCUMENT>
<TYPE>SC 13G
<SEQUENCE>1
<FILENAME>gbio-sc13g_123120.htm
<DESCRIPTION>SCHEDULE FILED TO REPORT ACQUISITION OF BENEFICIAL OWNERSHIP
<TEXT>
Document 1 - file: gbio-sc13g_123120.htm

</DOCUMENT>
</SEC-DOCUMENT>