(Yicai Global) Dec. 28 -- Alibaba Group Holding swelled the size of its stock buyback program by two-thirds in an attempt to halt a slide in the e-commerce giant’s share price after founder Jack Ma’s internet empire became the focus of an antitrust probe by Chinese regulators.

Alibaba will repurchase USD10 billion of its own shares, up from a planned USD6 billion, the Hangzhou-based company said in a filing to the Hong Kong Stock Exchange today. The buyback program, which began this quarter, will run for two years to the end of 2022.

In Hong Kong, Alibaba [HKG: 9988] fell almost 8 percent today to close at HKD211.40 (USD27.27), a level not seen since the end of June. In New York, its shares [NYSE:BABA] gave up 13.3 percent on Dec. 24 to end at USD222 each, also a six-month low.

Buybacks remove some of a public company’s outstanding shares from the market, with the aim of shoring up its stock price. 

Alibaba’s shares went into freefall on Dec. 24 when China’s market watchdog said it was investigating the tech behemoth for alleged unfair market practices. One of the key bones of contention is Alibaba’s practice of forcing vendors to sign exclusivity contracts that prevent them from selling on other platforms. Alibaba said it would actively cooperate with regulators.

Jack Ma’s Ant Group was also summoned for talks with China’s central bank and three financial watchdogs over the weekend and ordered to conduct a major shake-up of its mobile payment services. These include making the fintech firm’s transactions more transparent, obtaining the necessary licenses for its credit businesses and setting up a financial holding company.

China halted Hangzhou-based Ant’s USD35 billion initial public offering, which would have been the world’s largest to date, at the start of last month.

The Alibaba probe does not mean that China no longer supports the platform economy, an official at the market regulator in Zhejiang province, which is home to both Alibaba and Ant, said yesterday. Rather, the government aims to better regulate the e-business sector so as to ensure its healthy development and to help it contribute more to high-quality economic development.

But investors still sold shares of other Chinese tech giants today. Food delivery firm Meituan [HKG: 3690] dropped 6.9 percent to HKD260; Tencent Holdings [HKG: 0700] slid 6.7 percent to HKD510; and Alibaba rival JD.Com [HKG: 9618] fell 2.2 percent to HKD318.40.

Editor: Kim Taylor