The world's largest ever initial public offering (IPO) has been suspended just days before go-live.
Ant Group is a fintech giant established by China's wealthiest man, Jack Ma. The company was due to float simultaneously in Shanghai and Hong Kong on Thursday after raising $51 billion.
It would have had a market capitalisation of more than $435 billion, making it the biggest share market debut in history.
But in a remarkable development overnight, Chinese regulators reportedly stopped the float from going ahead.
The announcement on the Shanghai stock exchange forced its Hong Kong counterpart to also suspend Ant's public debut.
Reuters reported the suspension came after Ma and other Ant executives met with regulators on Monday.
Ant's online lending arm would require further scrutiny, the authorities reportedly told the executives.
"The Communist Party has shown the tycoons who's boss," GEO Securities chief, Francis Lun, told Reuters.
"Jack Ma might be the richest man in the world but that doesn't mean a thing. This has gone from the deal of the century to the shock of the century."
The surprise development sent shares of Ant's parent company Alibaba Group Holding Ltd (NYSE: BABA) into freefall on the New York Stock Exchange.
The stock lost 8.1% overnight, to mercifully close at US$285.57.
Alibaba is also listed as Alibaba Group Holding Ltd (HKG: 9988) in Hong Kong, which may also experience some turbulence Wednesday.
Ant Group started life in 2004 as a platform known as Alipay, as an escrow payments facilitator on Alibaba.
The company has since rebranded and broadened its offerings to lending, insurance and investment.
According to CBInsights, Ant Group increased its profit by more than 1,000% to $4.4 billion, while its revenue also went upwards 40% to more than $13 billion.
Just the Alipay part of the business facilitates more than 50% of mobile payments by volume in China.
Ant Group split off from Alibaba in 2011 to obtain a digital payments licence.
