Chinese e-commerce giant Alibaba will acquire a controlling stake in leading Southeast Asian online shopping platform Lazada for $1 billion, it said Tuesday as Jack Ma's company seeks to expand outside its home market.Alibaba's Taobao platform is estimated to have more than 90 percent of the consumer-to-consumer market in China, while its Tmall platform is believed to command more than half of business-to-consumer transactions. But its international commerce business only accounted for six percent of its revenue for the quarter ended in December, its latest earnings report showed.Alibaba is investing $500 million in newly issued Lazada shares and acquiring stock from some existing holders to take a majority stake in the firm for a total of around $1 billion.