YIZHENG Chemical Fibre has borne the brunt of the volatile stock market, closing up a meagre 1.89 per cent on its debut in the territory. Brokers could not give a reason for its performance, except that the stock missed the bull run enjoyed by mainland enterprises. Sentiment in the market had been uncertain, particularly about H-class counters, brokers said. Most were plagued by negatives, including an imminent listing of a second batch of Chinese enterprises, triggering heavy selling pressure. One analyst said: ''I am a bit surprised at the performance. People have the feeling that they have accumulated too many H shares.'' Despite the backdrop of a 3.08 per cent rise in the Hang Seng Index, four of the seven H shares traded were among yesterday's top 10 losers. A rumour circulated in the market that the debut by Maanshan Iron & Steel Co in November last year was being investigated. One analyst said: ''Most investors don't know much about the market. They are conservative and will believe what they hear. ''And the first thing is to sell the shares when any negatives come up. It has nothing to do with the company's fundamentals.'' Yizheng closed at $2.425, up 4.5 cents on its issue price of $2.38, with a heavy turnover of $291.3 million. Earlier it hit a high of $2.55. An official at S.G. Warburg - the issue sponsor - said one day's trade on the exchange could not represent Yizheng's strength. ''You can't help the market. The market was down by eight per cent when Yizheng's share offer opened in Hong Kong,'' he said. G.K. Goh Securities dealing manager Bobby Ho said investors who borrowed money to subscribe for the shares might find themselves making paper losses. He said the break-even price for those investors would be about $2.50. However, one analyst said: ''There cannot be too much disappointment, as the company was a strategic industry in China and has done well.''