Spark Therapeutics Inc. closed its underwritten public offering of 5,296,053 common shares to raise net proceeds of about $380.4 million.

The offering included the 690,789 shares sold under the full exercise of the underwriters' option to buy additional shares at the public offering price of $76.00 per share, less the underwriting discount.

J.P. Morgan Securities LLC, Goldman Sachs & Co. LLC and Cowen and Co. LLC acted as book-running managers for the offering.