Investors keen for a slice of the first initial public offering on the mainland in 15 months propelled Neway Valve (Suzhou) to a gain of more than 43 per cent on its trading debut yesterday. A flight of funds from existing stocks on the Shanghai exchange caused the benchmark index to drop nearly 1 per cent as it edged lower to a psychologically significant threshold. Neway's shares jumped 43.5 per cent to 25.34 yuan (HK$32) yesterday, while the Shanghai Composite Index shed 0.93 per cent to 2,004.95, barely holding above the 2,000-point level. Mainland investors, before the 15-month hiatus on new listings, had become accustomed to strong first-day gains of IPO shares, with most market newcomers surging at least 30 per cent. On the mainland, stocks are subject to a 10 per cent daily trading cap, but no trading limits are imposed on the first-day trading of newly listed stocks. Trading of Neway shares was halted just 10 seconds after the market opening yesterday as they climbed 10 per cent above the opening price of 21.19 yuan. The Shanghai Stock Exchange suspends trading for 30 minutes when new stocks climb 10 per cent from their opening prices, in a move to curb excessive speculation. The 30-minute trading halt failed to slow the buying momentum for the first IPO since October 2012, when the securities regulator decided to stem the flow of fresh equity to underpin a weak market. "The overall market is weak and disappointing," said retail investor Han Haifeng, who aims to join the rush for first-day gains after seeing Neway's rosy debut. "We have lost a large amount of money and I am not afraid of participating in another gambling game." The China Securities Regulatory Commission is stepping up its efforts to curb excessive pricing of new shares in a bid to protect small investors. On Thursday, the CSRC said it would investigate 13 underwriters and 44 institutional investors for questionable pricing behaviour during IPO consultations.