Chinese mainland companies sold US$18.9 billion worth of shares in Hong Kong last year, more than four times the amount raised at home after mainland regulators halted public share sales in May to allow for conversions of non-tradable stock.

The total includes US$15.3 billion raised in initial public offerings and US$3.6 billion from additional share sales, the China Securities Regulatory Commission said on its website.

Mainland companies raised 33.8 billion yuan (US$4.2 billion) from domestic share sales before the suspension.

China's regulators stopped new issues to avoid a flood of equity as companies pursued plans to make more than US$200 billion of mostly State-owned stock tradable.

The government may lift the ban in April or May, Shanghai Stock Exchange Executive Vice-President Zhou Qinye said last week.

The move would enable Hong Kong-listed companies, such as China Construction Bank Corp, to sell shares in the mainland.

"The reform will make the share structure simpler, and some Hong Kong-listed companies may return," said Lu Jiehua, an analyst at Shenyin Wanguo Securities Co. "China's stock market would be sidelined if all quality companies list overseas."

China is unifying different classes of shares in an attempt to bring the stock market more in line with global standards and make corporate management more accountable to shareholders.

Companies representing 30 per cent of the market's value have made their stock tradable so far, the exchange's Zhou said last week.

China Construction Bank, the mainland's third-biggest lender, in October raised US$9.2 billion selling shares in Hong Kong, the world's biggest initial public offering in five years.

Bank of Communications, the fifth-biggest lender, raised US$2.2 billion in July, among 14 mainland companies that sold shares for the first time in Hong Kong last year.

Many of mainland's most profitable companies have chosen to list overseas rather than on the nation's domestic stock exchanges in Shanghai and Shenzhen, including PetroChina Co, the nation's biggest oil company.

The combined market value of the mainland's 1,381 publicly traded companies dropped 12.5 per cent from a year earlier to 3.2 trillion yuan (US$400 billion) as of December 31, the stock market regulator said.

Trading turnover totalled 3.17 trillion yuan (US$390 billion) last year, contributing 10.3 billion yuan (US$1.27 billion) in stamp duty.

Allowing overseas-listed companies to sell shares in the mainland may help boost the total value of mainland's stock market to third in Asia by the end of next year from seventh, the Shanghai exchange's Zhou said last week.

He cited PetroChina, Construction Bank, Bank of Communications, and Shenhua Energy Co, mainland's biggest coal producer, as possible candidates.

Source: China Daily