According to a 8-K form submitted by Sohu.com to the U.S. Securities and Exchange Commission, the Chinese business-to-business e-commerce company Alibaba.com will invest USD15 million to acquire a 10% stake in Sogou.com, a subsidiary of Sohu.com.

The 8-K form shows that the search engine Sogou.com and its affiliates signed the first round preferred stock purchase agreement with investors on October 2, 2010. These investors included Alibaba.com, Yunfeng Fund, and Guangzi Group, an investment fund owned by Sohu.com’s chairman and CEO Charles Zhang.

Under the stock purchase agreement, Alibaba.com will acquire a 10% stake in Sogou.com for USD15 million, Yunfeng Fund will acquire a 16% stake for USD9 million, and Guangzi Group will acquire a 16% stake for USD24 million. Meanwhile, Sohu.com will maintain a 53% stake in Sogou.com.