China imposed a fine of 18.2 billion yuan ($2.8 billion) on Alibaba Group after an anti-monopoly probe, part of a regulatory crackdown that has raised concerns about the future of Jack Ma’s tech empire.

The penalty is equivalent to 4% of Alibaba’s domestic sales in 2019, China’s State Administration for Market Regulation said in a statement on Saturday.

Alibaba will also be required to implement "comprehensive rectifications,” including strengthening internal controls, upholding fair competition, protecting businesses on its platform and consumers’ rights, the regulator said. The company will be required to submit reports on self-regulation to the authority for three consecutive years.

Alibaba has been under mounting pressure from Chinese authorities since its founder Ma spoke out against China’s regulatory approach to the finance sector in October. Those comments set in motion an unprecedented regulatory offensive, including scuttling plans for Ma’s Ant Group Co.’s $35 billion initial public offering.

The company said it "sincerely” accepted the penalty and will comply.

"We will intensify our operation according to the law, further strengthen the construction of the compliance system based on innovation and development, and better fulfill social responsibility,” Alibaba said on Saturday.