Alibaba Group Holding Ltd. raised a proposed stock repurchase program by $4 billion to $10 billion, offering more support to shares battered by a widening antitrust investigation into the country’s most powerful internet corporations.

Once hailed as the standard-bearers of China’s economic and technological ascendancy, Alibaba and rivals like Tencent Holdings Ltd. now face increasing pressure from regulators worried about the speed with which they’re amassing hundreds of millions of users and gaining influence over almost every aspect of daily life. Alibaba’s stock is down roughly 30% from its 2020 peak, battered by the deepening scrutiny and allegations of monopolistic practices at the crown jewel of billionaire Jack Ma’s empire.

Beijing kicked off an antitrust investigation into Alibaba last week and dispatched officials to its Hangzhou headquarters, marking the formal start of the Communist Party’s crackdown on the company that made Ma the country’s best-known entrepreneur. On Sunday, Chinese regulators ordered Ma’s other online titan — Ant Group Co. — to return to its roots as a provider of payments services, threatening to throttle growth in its most lucrative businesses of consumer loans and wealth management.

Ma, the flamboyant co-founder of Alibaba and Ant, has all but vanished from public view since Ant’s initial public offering got derailed last month. As of early December, the man most closely identified with the meteoric rise of China Inc. was advised by the government to stay in the country, a person familiar with the matter has said.

Ma isn’t on the verge of a personal downfall, those familiar with the situation have said. His very public rebuke is instead a warning Beijing has lost patience with the outsize power of its technology moguls, increasingly perceived as a threat to the political and financial stability President Xi Jinping prizes most.