* KKR, Baring Private Equity weighing whether to invest - sources. : HONG KONG (Reuters) - Investment firms are exploring a buyout of Yum China Holdings Inc. (YUMC.N) in what could be one of Asia’s biggest M&A; deals this year, sources close to the situation told Reuters. Yum China, which had a market cap of $13 billion as of its closing price on Monday, was spun off from the KFC and Pizza Hut owner Yum Brands! Inc (YUM.N) in 2016 and later listed on the New York Stock Exchange.