13G Filing: EcoR1 Capital and Ovascience Inc. (NASDAQ:OVAS)

Page 2 of 7 – SEC Filing

1. Names of Reporting Persons.

EcoR1 Capital, LLC

2. Check the Appropriate Box if
a Member of a Group (See Instructions)

(a) X

(b)

3. SEC Use Only

4. Citizenship or Place of Organization Delaware

Number of
Shares
Beneficially
Owned by
Each Reporting
Person With:
5. Sole Voting Power -0-
6. Shared Voting Power 3,512,332
7. Sole Dispositive Power -0-
8. Shared Dispositive Power 3,512,332

9. Aggregate Amount Beneficially Owned
by Each Reporting Person 3,512,332

10. Check if the Aggregate Amount in
Row (9) Excludes Certain Shares (See Instructions) ______

11. Percent of Class Represented by
Amount in Row (9) 9.9%

12. Type of Reporting Person (See Instructions) OO

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