Alibaba Group Holding has agreed to buy a controlling stake in Southeast Asian online retailer Lazada Group for about US$1 billion, its biggest deal overseas, as the Chinese e-commerce giant seeks fertile new turf while growth slows at home, according to the South China Morning Post. Lazada, founded by Germany’s Rocket Internet in 2012, is headquartered in Singapore and also operates in Malaysia, Indonesia, the Philippines, Thailand and Vietnam. That affords Alibaba a chance to tap the region’s growth potential, but the market is also competitive and fragmented, with only a fraction of total retail sales currently conducted online.