Wal-mart is investing in Yihaodian, a Shanghai-based B2C megastore, the move came after its US$300 million acquisition of social media startup Kosmix and its joint investment in 360buy, highlighting the giant U.S. retailer’s big appetite for both China and online shopping.

Launched in July 2008, Yihaodian served customers with more than 100,000 of goods ranging from foods and drinks to maternity-children supplies to electric appliance. The company operates logistics and warehouses in Shanghai, Beijing and Guangzhou, while offering overnight delivery services in these three cities. Yihaodian’s sales revenue reached more than RMB 800 million (US$120 million), with an average monthly increase of over 28% in sales.

Both Yihaodian and Wal-mart didn’t disclose details on the stake buying, but according to TechwebChina PingAn, one of the biggest insurance company in China, acquired 80% of the online retailer’s shares last year. So it stood to good chance that Wal-mart could have purchased its share from China PingAn.