China has opened an antitrust investigation in Alibaba

“This is an important step in strengthening antitrust oversight in the online sphere,” reads an article published on the paper’s website Thursday morning. “This will be useful for regulating the regulated sector and promoting long-term healthy platform development.”

Politically savvy and investors in China have speculated for years that national leader Xi Jinping will be tempted to go against Alibaba and Mr. Mao, worried that their influence is a growing insult to the Communist Party and could undermine control over market and internet capital. But until recently, Chinese regulators have been moving cautiously.

Two recent meetings of the party leadership indicated that Mr. Xi was considering action.

The Politburo, a council of the party’s 25 top officials that meets every month or so, called for stronger antitrust efforts when it met this month, although an official statement from the meeting did not specify any companies or sectors. A few days later, the call was followed by an even clearer request for an annual meeting of the party’s leadership on economic policy, which hinted that companies with online platforms would face greater scrutiny.

The Chinese government “supports the innovative development of platform companies and the strengthening of their international competitiveness,” according to an official summary of the meeting. “At the same time, development must be regulated in accordance with the law and digital rules must be improved.”

Regulators should “resolutely oppose monopolies and inappropriate competitive behavior,” the meeting summarized.

Mr Ma’s statements on financial regulations, made at a conference in Shanghai in October, appear to have helped catalyze an official response against Ant and Alibaba.

“In Chinese culture, if you’re a rich guy and you have very strong economic power and social influence, then you’re politically dangerous and you have to be at a very low level to be sure,” said Gary Liu, an independent economist from Shanghai.

People in China see Mr. Ma and Antu as the main beneficiaries of the authorities’ cautious approach to regulating internet financing. “But still, he complained,” Mr. Liu said. “In Chinese culture, such a person is not respected.”

Chris Buckley and Keith Bradsher contributed to the reporting.