ZymoGenetics to sell 12 million shares

Jan 6 (Reuters) - Biotechnology firm ZymoGenetics Inc (ZGEN.O) said it will sell 12 million common shares in a public offering. Shares of the company fell 11 percent to $6.00 in trading after the bell. The proposed offering amounts to about 17 percent of the company's total outstanding shares of about 69.3 million as of Oct. 30, 2009. The company plans to grant underwriters an over-allotment option to purchase up to an additional 1.8 million shares. A portion of the net proceeds from the offering will be used to support the commercialization of its synthetic blood-clotting enzyme Recothrom, the company said in a statement.