Investors were left reeling by the suspension of Ant Group’s $37 billion stock market listing on Tuesday, with many having spent weeks studying the deal and lobbying bankers for shares in what was set to be the world’s biggest initial public offering.

Ant halted its planned Shanghai and Hong Kong listings less than 48 hours before it was due to go public following a meeting by its billionaire founder Jack Ma and Chinese financial regulators.

Ant apologised to investors in a stock market filing for “any inconvenience” and said it would follow up with them, but gave scant details on what the problem was aside from calling it a “major event.”

“There has been so much excitement around this IPO and there is clearly deep disappointment from the markets about this unexpected curve ball,” said Victoria Scholar, market analyst at IG.

Investors were wary that regulators’ problem with the deal could spread beyond Ant to other Chinese technology stocks.

“For now, markets will sell off Alibaba and likely Tencent as well as other relevant exposures,” said Dave Wang, a portfolio manager at Nuvest Capital in Singapore.

“If this is an isolated incident to Ant, then the New Economy stocks that have done well so far should be fine … if not, markets may start to price in uncertainty on tighter regulations on private enterprises and we could see a significant pullback on Chinese growth stocks.”

An investor at a state-backed firm in China, who had a pre-IPO holding in Ant, said the delay had left them questioning whether it would become politically difficult to hold the stock even if the IPO gets back on track.

More than $3 trillion just from retail investors had been placed in bids for Ant, a factor some said was likely to have prompted a tougher line from Chinese supervisors.

“It’s quite clear that the magnitude of the oversubscriptions and the influence of Alibaba have become a source of concern for the regulators,” said Justin Tang, head of Asian Research at United First Partners in Singapore.

For William de Gale, cofounder and lead portfolio manager at BlueBox Asset Management, who had opted not to take part in the deal from the get-go, the suspension was vindication for their stance on Chinese financial companies.

“I think this demonstrates why we don’t particularly like these companies – there is always a risk of capricious behaviour by management or regulators, neither of whom are subject to reliable or predictable governance,” he said.