Trip.com, the prominent Chinese online travel company, saw its shares plummet by 19.23% in Hong Kong on Thursday. This sharp decline followed the initiation of an antitrust investigation by Beijing, making it the most significant drop among companies in the Hang Seng index.

This downturn also represents the worst single-day performance for Trip.com’s stock in Hong Kong since its listing in April 2021. The stock had already seen a 17% decrease in value during New York trading on Wednesday.

The State Administration for Market Regulation in China announced late Wednesday that it had launched an investigation into Trip.com over “suspected abuse of its dominant market position and monopolistic practices,” as translated from Mandarin by CNBC.

Trip.com is the largest online travel provider in Asia by market cap, and one of the biggest globally. The company has stakes in UK flight aggregator Skyscanner, Indian travel company MakeMyTrip, as well as several Chinese travel providers.

Trip.com said in a statement it would “actively cooperate” with the investigation, and added its business operations were functioning as usual.

The case could have long term ramifications for the company, according to Morningstar senior equity analyst Kai Wang.

Wang said that “multiple local tourism associations have complained that Trip.com is committing the same violations as the other two platforms, where it is forcing local merchants to sign exclusive agreements with the platform.” Trip.com will then increase commissions from the merchants after these agreements are signed.

Citing previous high-profile antitrust cases involving Alibaba and Meituan, as well as past government warnings, Wang said that Trip.com could incur a “hefty fine.”

SAMR investigated Chinese tech giant in Alibaba in 2021, fining the firm a record 18.2 billion yuan ($2.8 billion) after it was found guilty of monopolistic practices.

“This is not the first time Trip.com has run afoul with the government for consumer violations, as the company was fined for forced bundling of value-added services back in 2017. This could also infuriate the government even more given its repeat offender status,” he added.

The probe into Trip.com comes as Chinese tourism is expected to surge this year, with travel marketing and technology firm China Trading Desk estimating that mainland Chinese travelers are expected to take about 165 million to 175 million cross-border trips in 2026, up from an estimated 155 million last year.

The Chinese New Year holiday, which sees hundreds of millions of people travel back to their hometowns, will be observed between Feb. 15 and Feb. 23.

Travel consultancy firm Dragon Trail International said that in 2025, 501 million Chinese traveled domestically during the Chinese New Year holiday period, a 5.9% year-on-year increase. Tourism spending during the period reached 6.77 billion yuan, a 7% increase.