THE impressive subscription rate of Yizheng Chemical Fibre's public share offer failed to prop up other H shares issued by Chinese state-owned enterprises, as the broader market tested the year's session lows. The H shares skidded by between two and 15 per cent, with Guangzhou Shipyard bearing the brunt, losing 45 cents to $2.925. Tsingtao Brewery was least affected, edging down 15 cents to $7.00. Shanghai Petrochem, which was seen closely linked to the performance of Yizheng because of similarities in their business activities, was also down 15 cents, or 6.25 per cent, to $2.25. Earlier this week, Shanghai Petrochemical was reportedly being bought by institutional players who found the company a bargain in terms of price/earnings ratio compared with Yizheng's 13.83 times on 1993 projected earnings. But the buying spree quickly faded. Keith Wu, director at Dao Heng Fund Management, expected Shanghai Petrochemical could move in tandem with Yizheng's share price performance and eventually both counters would trade at a similar price/earnings multiple. Shanghai Petrochem traded at 12.5 times its 1993 estimated earnings, or 15 times 1994 prospective earnings, based on James Capel's profit projection. Yizheng, as the seventh state-owned enterprise being listed here, received 20 times subscription of its $714 million share public offering in Hong Kong. Its tranche of H shares offered to international investors, raising $1.67 billion, was nine times subscribed. Billy Chan, an investment manager at GT Management, regarded the public subscription rate as satisfactory against a backdrop of the market rout, indicating that investment interest in the Chinese polyester maker was great. But he asserted that it would be ''a circular argument'' to say that the existing H shares would be bolstered by the warm market reception of Yizheng, because some investors, on the contrary, would cash in existing Chinese shares holdings to buy into thelatest candidate. ''In the long term, the co-relation correlation will not exist,'' said Mr Chan, ''because fund managers will focus on individual companies' fundamentals.'' He said Yizheng and Shanghai Petrochem were tapping different market segments, with the former a single-product company and the latter a fully integrated manufacturer. He said he found Yizheng more preferable in view of less uncertainties in the area of price deregulation. He also expected the company's profit margin to get a lift from the completion of a new polyethylene terepthalate (PTA) plant which would also reduce its foreign exchange exposure.