Alibaba Group Holding Ltd. (NYSE: BABA) increased its stock repurchase program late Sunday from $6 billion to $10 billion, but shares still sank in Hong Kong trading amid an antitrust investigation by Chinese regulators. In a statement Sunday, Alibaba said its board of directors had approved the larger repurchase, to last through 2022. The stock repurchase program began earlier this quarter. Alibaba’s stocks are trading down 30% since November’s highs as a result of antitrust investigation.