Ant IPO-approval process under investigation by Beijing

Beijing is investigating how Jack Ma won speedy approvals for his Ant Group Co.’s stock listing last year, according to people with knowledge of the matter, signaling that state actors are getting embroiled in the crackdown on the tech billionaire.

The central-government investigation, which started early this year, focuses on regulators who greenlighted the initial public offering, local officials who advocated it and big state firms that stood to gain from it. Mr. Ma’s relationships with these state stalwarts are being examined as part of the scrutiny, according to the people.

The probe means uncertainty continues to loom over the future of Ant and controlling shareholder Mr. Ma. The usually flamboyant entrepreneur has kept a low profile since the IPO was stopped last-minute in November.