Chinese top hypermarket operator Sun Art Retail Group Ltd jumped?25 percent on its trading debut on Wednesday following a $1.1 billion Hong Kong IPO as investors bid up the shares, betting on strong growth in Chinese mainland's consumer demand.

Sun Art -- a joint venture between Taiwan conglomerate Ruentex Group and privately held French retailer Groupe Auchan SA -- sold shares at the top of the marketing range in early July, defying a slump in the world's biggest IPO market.

By 0122 GMT, Sun Art shares were trading at HK$9.00 each, compared with the IPO price of HK$7.20 each, while the benchmark Hong Kong share index was down 0.4 percent. The stock was quoted up 18 percent in gray market trade on Tuesday, according to Phillip Securities.

The company had delayed its debut by nearly two weeks due to discrepancy in the IPO prospectus relating to historical earnings per share figures.