Athersys Inc. plans to start an underwritten public offering of its common shares.

The company will grant underwriters the option to buy up to an additional 15% of the common shares offered.

Athersys plans to use the net proceeds for working capital, general corporate purposes, funding for its phase 3 MultiStem administration for stroke treatment and enhanced recovery clinical study and other ongoing clinical programs.

William Blair & Co. LLC is acting as sole book-running manager, and Needham & Co. LLC is acting as lead manager for the offering.