Chinese financial technology giant Ant Group looks set to make the world's largest stock market debut.
Ant, backed by Jack Ma, billionaire founder of e-commerce platform Alibaba, is to sell shares worth about $34.4bn (£26.5bn) on the Shanghai and Hong Kong stock markets.
Advisers to Ant set the share price on Monday amid reports of very strong demand from major investors.
The previous largest debut was Saudi Aramco's $29.4bn float last December.
Ant, an online payments business, is only selling about 11% of its shares. But the pricing values the whole business at about $313bn.
Mr Ma's Ant shares are reportedly worth about $17bn, taking his net worth to close to $80bn and confirming him as China's richest man.
Ant runs Alipay, the dominant online payment system in China, where cash, cheques and credit cards have long been eclipsed by e-payment devices and apps.
The company is expected to make its dual listing in Shanghai and Hong Kong next week, underling the latter exchange's growing importance as a financing hub.
The Trump administration has threatened to limit Chinese firms' access to US capital markets, a move that is part of the long-running trade row between Washington and Beijing.
Chinese tech firms, including NetEase and JD.Com, have already raised billions by selling their shares through the Hong Kong stock market.
According to the Bloomberg news agency, Mr Ma told a conference in China on Saturday that the flotation would be of huge significance for Shanghai and Hong Kong.
"This was the first time such a big listing, the largest in human history, was priced outside New York City," he told the Bund Summit.
"We wouldn't have dared to think about it five years, or even three years ago," said Mr Ma.