Arrowhead Pharmaceuticals Inc. raised about $266.8 million in gross proceeds via a public offering of its common shares.

The biotechnology company sold 4.6 million shares at $58 apiece, including 600,000 additional shares as part of underwriters' overallotment option.

The Pasadena, Calif.-based company, that develops therapies for the treatment of rare genetic disorders, plans to use the net proceeds from the offering for research and development activities. Funds will also be used for the acquisition of complementary businesses, products and technologies.

Goldman Sachs & Co. LLC, Jefferies LLC and Piper Jaffray & Co. were the book-running managers for the offering, while Cantor Fitzgerald & Co. acted as a passive joint book runner, and Robert W. Baird & Co. Inc. and B. Riley FBR Inc. acted as co-managers.