Its shares closed at 3.28 yuan (41.5 US cents) in Shanghai, up 5.13 per cent from its IPO (initial public offering) price of 3.12 yuan (39.5 US cents). Investors oversubscribed the stock 26 times in the world's biggest IPO that raised US$19.1 billion.

In Hong Kong, the bank's H shares closed at HK$3.52, up 14.66 per cent from its IPO price of HK$3.07.

Share prices fluctuated between HK$3.63 and HK$3.50, with the peak price 18 per cent higher than the IPO price. Bullish sentiment lifted the benchmark Hang Seng Index to a six-year high in the morning session.

It was the first-ever simultaneous listing in both Hong Kong and Shanghai by a giant mainland lender. The IPO represents about 15 per cent of the bank's enlarged share capital.

"It is the day of the ICBC... It surely will attract many other companies to follow suit and launch dual listings, because the A-share market policy and regulations are getting sound and mature and the economic gap between Hong Kong and the mainland is narrowing," said Andrew To, director of Hong Kong-based Taifook Securities.

However, market watchers were a little disappointed, as they had expected the shares to rise as much as 12 per cent on the Shanghai market.

"The closing price was lower than expected," said She Minhua, a banking analyst with CITIC China Securities. He had expected the shares to close at up to 3.5 yuan (44.3 US cents) on their debut.

Bank of China (BOC), the country's second biggest lender, made a strong debut by rising as high as 23 per cent from its IPO price of 3.08 yuan (39 US cents) on July 5.

BOC shares closed at 3.30 yuan (41.8 US cents) on Friday in Shanghai.

"ICBC shares should be higher than those of the BOC, given the former's largest operating network across the country. And the ICBC is also expected to increase its revenue on bank commission fees faster than the BOC," She said.

The benchmark Shanghai composite index closed at 1,807.18, down 0.19 per cent.

The Hang Seng Index closed at 18,297.55, 0.31 per cent lower, after rising 92.72 points to 18,446.46 by midday.

Analysts attributed the fluctuation to the speculative activities of investors who want to buy once the stock opens and sell before the market closes.

ICBC Chairman Jiang Jianqing said at the stock opening ceremony that he was "very, very satisfied" with the listing and the stock's debut performance.

"The listing was very successful. It will help improve our management. The strong demand reflects the acceptance by the international investment community of the ICBC," Jiang told reporters.