As one of the giant share sales of the year, BOC's offer has attracted overwhelming demand from Hong Kong tycoons and key international players even though it has not yet been launched.

Since last year the lender has brought in several strategic investors that have taken up a combined 20.74 per cent stake. They include a consortium led by Royal Bank of Scotland, the Singapore government investment arm Temasek Holdings, UBS, the Asian Development Bank and the National Social Security Fund.

Cheung Kong (Holdings) chairman Li Ka-shing, Henderson Land Development chairman Lee Shau-kee, New World Development chairman Cheng Yu-tung and many other tycoons are expected to snap up US$1 billion worth of BOC's shares in the offer.

The arrangers had indicated that the lender would earmark about US$1 billion worth of offer shares to about eight tycoons but the amount had yet to be finalised.

'About 12 tycoons have shown interest in the offering but the arrangers just can't satisfy everyone and cut the numbers in half. They initially indicate that the lender is likely to be priced at about two times book value,' a source said.

But the fact that a large portion of BOC's shares is held by the strategic investors has prompted the stock exchange to question whether their holdings should be counted in the public float as those investors may have business ties with the lender in the future.

Royal Bank of Scotland, which bought a 10 per cent stake through a consortium including the Li Ka Shing Foundation and Merrill Lynch, has been given an exclusive strategic partnership with BOC in areas such as credit cards, wealth management, corporate banking and insurance.

According to the listing rules, for any new offerings, at least 25 per cent of the company's issued share capital should be held by the public. But companies can apply to the stock exchange for a waiver of the public float requirement, lowering the threshold to 15 per cent if its market capitalisation at the time of listing exceeds $10 billion.

BOC's market capitalisation will enable it to be granted the public float waiver. But if the exchange had refused to count the shares held by strategic investors in the public float, the lender would have needed to pump up its fund-raising significantly to satisfy the public float requirement, said a banker familiar with listing rules.

Sources said the listing committee had basically agreed to count those shares held by strategic investors in the public float, clearing the way for the launch next month.

According to standard practice, a formal listing hearing is likely to follow as soon as next week, which means BOC can start pre-marketing its float early next month if it gets the go-ahead.

The lender is tentatively set to kick off its retail offering in the second half of next month and start trading in early June.