THE A shares of Yizheng Chemical Fibre Co jumped 28 per cent on their debut on the Shanghai Stock Exchange yesterday, although analysts said the price could retreat. The polyester-fibre maker ended the first day's trade above the issue price of 2.68 yuan (HK$2.45) at 3.42 yuan, against a four per cent drop in the Shanghai A index. Yizheng, which caught the Hong Kong stock market by surprise with the proposed issue to convert 400 million A shares into H shares, rose 1.83 per cent to $2.775 in the territory yesterday. The Hang Seng Index rose 0.53 per cent. The death of China's veteran revolutionary leader Chen Yun appeared to have little impact on Yizheng's debut and China's stock market as a whole. Shanghai Shenyin Securities trader Yang Jian said: 'The stock market is directed more by its own development than anything.' About 120 million Yizheng A shares, representing 60 per cent of the total 200 million shares on offer, changed hands yesterday, giving a turnover of nearly 410 million yuan. This in turn accounted for 22 per cent of the 1.86 billion yuan worth of A shares traded on the Shanghai stock exchange yesterday. Traders generally praised the performance of Yizheng's A shares, seen as a welcome boost to the bearish mainland stock market, plagued by jitters over the inflated economy and austerity measures. Yizheng issued 200 million A shares, ranking it with Shanghai Petrochemical Co and Maanshan Iron & Steel Co as the biggest capitalised stocks on the Shanghai exchange.