China's shock decision to suspend the $35bn float of Ant Group hit shares of founder Jack Ma's Alibaba on Wednesday.
Shanghai's stock exchange announced the decision on Tuesday, less than 48 hours before shares were to begin trading and a day after Mr Ma was summoned by regulators.
The move was quickly interpreted as a signal from Beijing that officials were uncomfortable with the enormous influence of Ant Group, which has helped revolutionise commerce and personal finance in China but eroded the power of state financial institutions.
"The Party has once again reminded all private entrepreneurs that no matter how rich and successful you are it can pull the rug out from under your feet at any time," China-watcher Bill Bishop wrote in his Sinocism newsletter.
Hong Kong's exchange, where Ant Group shares were also to be listed, said the float would be postponed there as well.
Thursday's planned listings would have been the culmination of the world's biggest float.
Alibaba's Hong Kong-listed shares plunged nearly 10pc at the start of trading on Wednesday before closing 7.5pc lower. New York-listed shares fell 8.1pc on Tuesday.
The surprise suspension followed recent warnings in Chinese state media about potential financial instability from Ant Group's rapid growth and after Mr Ma triggered a backlash with comments late last month about regulators.
He criticised regulators as heavy-handed, out of touch with the needs of regular consumers and blamed them for stifling fintech innovation.
Speculation was rife that Mr Ma's comments were the last straw for the government.
Ant's Alipay platform has helped revolutionise commerce and personal finance in China, with consumers using the smartphone app to pay for everything from meals to groceries and travel.
But Ant Group, which has more than 700m monthly active users, has also stepped on toes in China's tightly state-controlled finance sector by venturing into personal and business lending, wealth management and insurance.
China has moved over the past three years to rein in mounting debt levels in the world's second-largest economy, and in recent weeks announced new regulations specifically targeting online lending.
"The main issue that the authorities are uncomfortable with is the line that allows fintech to be subjected to lesser scrutiny than its [state-owned] banks but could also well contribute to systemic risks," said Dave Wang at Nuvest Capital.
The comments by Mr Ma - Ant Group's controlling shareholder, one of China's richest and most powerful business figures, and a member of the ruling Communist Party - have cost him dearly.
The float would have made Ma Asia's richest person, but instead his net worth tumbled by about $3bn after Alibaba's US-listed shares plunged.
A Sunday commentary in the state-controlled Financial News warned of internet giants like Ant Group getting too big, saying any resulting systemic problems "will lead to serious risk contagion".
The state-owned Economic Daily newspaper responded Tuesday to the suspension calling it a demonstration of regulators' determination to "safeguard the interests of investors".
Ant said on Tuesday it "sincerely apologises ... for any inconvenience caused by this development" and that it would cooperate with regulators.
The firm said it would refund retail investors, though it was not clear when the listing might eventually go ahead.
But Wang of Nuvest Capital said he expected the hold-up to be a "short-term" affair while new rules were written and companies made adjustments.