Shares in Industrial and Commercial Bank of China (ICBC), which raised $19 billion in the world's largest stock sale, are set to rise as much as 20 per cent in their Hong Kong debut today as investors who failed to secure enough IPO shares crowd into the secondary market.

The lender, making the first simultaneous Hong Kong and mainland listing, is expected to see its Shanghai shares rise by a more modest 10 per cent as local shares in rivals, Bank of China and China Merchants Bank, have traded below their Hong Kong counterparts.

The stock sale was the most popular in Hong Kong history, and unmet demand for shares, combined with a market that hit a record high close yesterday and an offering priced at a discount to peers, should lift ICBC shares by between 15 per cent and 20 per cent on their first day in Hong Kong, market watchers said.

The IPO, about 75 per cent of which was sold to Hong Kong and global investors and the remainder on the mainland, surpasses Japan's NTT Docomo, which raised US$18.4 billion in 1998, as the world's largest share sale. An overallotment option is expected to lift ICBC's deal size to US$21.9 billion.

"As demand for the offering was strong, many institutional investors plan to buy shares in the market after they only received a small percentage of the IPO shares they sought," said Steven Leung, director of institutional sales at UOB-Kay Hian in Hong Kong.

ICBC priced its IPO at the top of an indicated range - HK$3.07 in Hong Kong and the equivalent 3.12 yuan on the mainland - after attracting demand of about US$400 billion for the Hong Kong portion of its deal and 780.7 billion yuan (US$99 billion) for its domestic deal.

Shares in ICBC changed hands for up to HK$3.45, a gain of 12.4 per cent, in grey market trading, and were quoted in the HK$3.42-HK$3.44 range yesterday afternoon, according to electronic trading platform Instinet.

Rivals China Construction Bank and Bank of China saw their shares end flat and up by 15.3 per cent, respectively, in their Hong Kong debuts. Construction Bank trades 55 per cent above its IPO price and Bank of China is up 15 per cent.

Investors have clamoured for shares of mainland banks as a proxy to take advantage of its 10 per cent-plus economic growth and a consumer lending market in its early stages. That has helped offset concerns about credit quality and lending practices at mainland banks.

"ICBC's warrants and options are available in the first trading day, with the strong liquidity in the Hong Kong stock market, which will boost its H-shares performance," said Ben Kwong, chief operating officer at KGI Asia.

ICBC's domestic debut is expected to be less robust.