As of now, the $9.7 billion offering is the world's biggest since a $10.6 billion IPO by AT&T Wireless Services Inc. in April 2000. It would be the biggest IPO ever for China.

The Chinese banks are dwarfed by international competitors such as Bank of Tokyo-Mitsubishi UFJ Ltd., which holds assets worth about 190 trillion Japanese yen ($1.6 trillion) and Citigroup with $1.55 trillion in assets.

But investors are attracted less by the size of the banks than the allure of China's economy, which has been expanding at a rate of about 10 percent for several years ¡ª and the performance of other banks' shares, analysts say.

China Construction Bank Corp., the country's third-biggest lender, has seen its share price rise about 50 percent since its $9.2 billion IPO in October. Shanghai-based Bank of Communications Co.'s share price has more than doubled.

"Some people were holding out, they were not convinced by the story, but then they were kicking themselves after the stock price" for other banks rose, said Wei of Moody's in Hong Kong. "So now there's a speculative effect where investors are being egged on to invest by others."