X0306 4 2015-10-07 0 0001609351 Spark Therapeutics, Inc. ONCE 0001631262 Marrazzo Jeffrey D C/O SPARK THERAPEUTICS, INC. 3737 MARKET STREET, SUITE 1300 PHILADELPHIA PA 19104 1 1 0 0 Chief Executive Officer Common Stock 2015-10-07 4 S 0 900 50.40 D 379100 D Common Stock 2015-10-07 4 S 0 24117 48.33 D 354983 D Common Stock 2015-10-07 4 S 0 25000 47.02 D 329983 D Common Stock 2015-10-09 4 S 0 4983 47.48 D 325000 D Common Stock 2015-10-09 4 S 0 20000 48.17 D 305000 D The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $48.15 to $48.50, inclusive. The reporting person undertakes to provide to Spark Therapeutics, Inc., any security holder of Spark Therapeutics, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (1) to this Form 4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $47.00 to $47.15, inclusive. The reporting person undertakes to provide to Spark Therapeutics, Inc., any security holder of Spark Therapeutics, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (2) to this Form 4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $47.75 to $48.58, inclusive. The reporting person undertakes to provide to Spark Therapeutics, Inc., any security holder of Spark Therapeutics, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (3) to this Form 4. /s/ Joseph W. La Barge, attorney-in-fact for Jeffrey Marrazzo 2015-10-09