China has launched an antitrust investigation into Alibaba (BABA) as it steps up scrutiny of the country's rapidly growing internet firms. The State Administration for Market Regulation, China's top market regulator, said Thursday that it would probe alleged monopolistic behavior by Alibaba, Jack Ma's online shopping and cloud computing giant. It gave few details but said it would investigate the company's practice of requiring merchants to sign agreements that prevent them selling products on rival platforms, known as "choosing one from two." Separately, the People's Bank of China announced that the country's four financial regulators will summon Ant Group, Alibaba's financial affiliate, to a meeting in the coming days. The meeting would "guide Ant Group" to implement financial supervision and regulate its services, the central bank said in a statement.