Arena Pharmaceuticals Inc. completed an underwritten public offering of its common shares, raising about $405.7 million in gross proceeds.

The San Diego-based biopharmaceutical company issued 9,775,000 common shares at $41.50 apiece. The total shares sold included 1,275,000 shares, which were issued as part of the full exercise of the underwriters' option to buy additional shares.

Arena Pharmaceuticals plans to use net proceeds to develop its clinical candidates, including phase 3 programs for etrasimod to treat ulcerative colitis and ralinepag for treating pulmonary arterial hypertension.

In addition, the company plans to use the net proceeds for general corporate purposes, including working capital and costs associated with manufacturing services, and for capital expenditures.

Citigroup, Leerink Partners, Cantor Fitzgerald, Credit Suisse and RBC Capital Markets acted as joint book-running managers, while Guggenheim Securities and JMP Securities acted as co-managers for the offering.