EDITAS MEDICINE INC

Ticker: EDIT CUSIP: 28106W103 Class: Stock

Flagship Pioneering, LLC's Holding History (CIK: 0001400240)

Note: Option positions (PUT/CALL) are excluded.

Q4 2017

Shares 1,674,435 Value ($000) $51,455 Avg Close $25.18 Range $20.29 - $32.85

Q3 2017

Shares 1,674,435 Value ($000) $40,203 Avg Close $19.03 Range $15.28 - $24.50

Q2 2017

Shares 3,376,184 Value ($000) $56,652 Avg Close $18.02 Range $13.12 - $22.74

Q1 2017

Shares 3,376,184 Value ($000) $75,356 Avg Close $20.72 Range $16.30 - $29.20

Q4 2016

Shares 3,455,316 Value ($000) $56,080 Avg Close $15.18 Range $12.43 - $18.94

Q3 2016

Shares 3,455,316 Value ($000) $46,578 Avg Close $20.49 Range $13.10 - $28.63

Period	Shares	Value ($000)	Average Close	Price Range
Q4 2017	1,674,435	$51,455	$25.18	$20.29 - $32.85
Q3 2017	1,674,435	$40,203	$19.03	$15.28 - $24.50
Q2 2017	3,376,184	$56,652	$18.02	$13.12 - $22.74
Q1 2017	3,376,184	$75,356	$20.72	$16.30 - $29.20
Q4 2016	3,455,316	$56,080	$15.18	$12.43 - $18.94
Q3 2016	3,455,316	$46,578	$20.49	$13.10 - $28.63