Spark Therapeutics Inc. priced an offering of 4,605,264 common shares at $76 apiece for expected net proceeds of about $330.8 million.
The company also granted underwriters an option to buy up to 690,789 additional shares.
The offering is expected to close by Aug. 9, subject to customary closing conditions.
J.P. Morgan Securities LLC, Goldman Sachs & Co. LLC and Cowen and Co. LLC are acting as book-running managers for the offering.