'Given the strong operating performance of Alibaba.com and the increased demand for our shares, we believe that releasing the locked-up shares into the unrestricted public float will help increase the liquidity of our shares and improve their attractiveness for institutional investors,' said Maggie Wu Wei, the chief financial officer of Alibaba.com.

The company, a unit of Hangzhou-based Alibaba Group, estimated the early release would swell the unrestricted public float of its shares by 14 per cent.

It said there was no plan to pursue any new equity financing.

'We have no insight into what our cornerstone investors will do [with their newly unlocked shares]. We do know that the shares have performed extremely well, especially in the past six months,' said John Spelich, a vice-president for international corporate affairs at Alibaba Group.

The eight cornerstone investors are Yahoo, AIG Global Investment Corp (Asia), Foxconn (Far East), Baldonna Investments, Finawood Investments, Honeybush, Cisco Systems International and Industrial and Commercial Bank of China (Asia).

Yahoo directly owns about 1.14 per cent of Alibaba.com and holds a 40 per cent stake in Alibaba Group.

Alibaba.com, which has 6.9 billion yuan (HK$7.83 billion) in cash and no debt, has seen its share price rise 151.25 per cent to yesterday's close of HK$14.02 from HK$5.58 at the end of last year.

In a report, Citigroup analysts upgraded Alibaba.com to 'buy' from 'sell', based on the steady growth of its paying customers amid the economic slowdown.

The mainland firm's first-quarter results showed it added a record net 49,544 paying members for a worldwide total of 481,575, up 47.22 per cent from 327,118 a year earlier.

Revenue in the three months to March grew 18.6 per cent to 806.6 million yuan from 680.1 million yuan. Net profit dropped an expected 15.7 per cent to 253.4 million yuan from 300.7 million yuan, as Alibaba.com increased spending on programmes to support members, employees and product development.