Chinese regulators on Thursday announced an anti-monopoly investigation of e-commerce giant Alibaba Group, stepping up the ruling Communist Party’s efforts to control fast-growing tech industries.

President Xi Jinping’s government worries about the dominance of competitors such as Alibaba, the world’s biggest e-commerce company by sales volume, and Tencent Holding, operator of the popular WeChat messaging service and Asia’s most valuable tech company.

Regulators appear to be especially concerned about controlling private sector companies that are expanding into online banking at a time when Beijing is trying to reduce financial risks.

The ruling party says anti-monopoly enforcement, especially in tech industries, will be a priority next year.

Since early November, regulators have tightened the reins by suspending the stock market debut of an online finance platform affiliated with Alibaba and summoned industry executives to warn them against trying to suppress competition.

“The era of free growth and ultra-high growth is really over,” said Francis Lun, CEO of Geo Securities Ltd in Hong Kong. “The government will decide what you can do.”

Thursday’s announcement said the state administration of market regulation is looking into Alibaba’s policy of “choose one of two”, which requires business partners to avoid dealing with its competitors. The one-sentence statement gave no details of possible penalties or a timeline to announce a result.

Proposed rules issued in November would ban exclusive contracts, subsidies and other tactics regulators say hurt competition.