Simpson Thacher & Bartlett and Skadden, Arps, Slate, Meagher & Flom have had the lead roles on Chinese e-commerce giant Alibaba Group Holding Ltd.’s buyout of mobile web browser developer UCWeb Inc.

Alibaba, which already owns 66 percent of UCWeb, is buying the remaining shares. Terms of the deal were not disclosed, but the Wall Street Journal reported that UCWeb chief executive officer Yu Yongfu told staff at an internal meeting that the deal valued the company at more than double the $1.9 billion Alibaba rival Baidu Inc. paid to acquire smartphone app store 91 Wireless Websoft Ltd.