Alibaba has a new challenger, and it’s backed by China’s three wealthiest men. China’s Dalian Wanda Group, led by the country’s richest billionaire Wang Jianlin, plans to launch a $813 million (5 billion yuan) e-commerce platform with Baidu and Tencent, according to multiple media reports that cited sources familiar with the matter. The deal will mark the most high-profile challenge by far to Alibaba’s dominance in the country’s fast-growing e-commerce market.