Shares in Hong Kong Exchanges and Clearing fell 3.59 per cent yesterday to HK$184.90, extending their four-day decline to 13.76 per cent as investors worried that the weakening United States economy will affect trading volumes. Since its peak at HK$268.60 in November, the stock has slumped 31 per cent, cutting the value of the government's stake in the exchange operator by about HK$5.2 billion over the period. Still, as the government bought its 5.88 per cent stake at HK$155.40 a share, it is sitting on a paper profit of 25 per cent or HK$1.82 billion. Legislators and some market players had criticised the government's purchase as market intervention but Financial Secretary John Tsang Chun-wah defended the deal as necessary to further the exchange's plans on the mainland, including a possible share swap with the mainland exchanges. Louis Tse Ming-kwong, director of VC Brokerage, said the drop in the share price was in line with the Hang Seng Index decline, as fund managers were selling on worries over the US economic outlook. 'Weaker stock market sentiment would affect the exchange's turnover and hence its income level,' he said. Meanwhile, HKEx yesterday said it would launch the Mini-Hang Seng China Enterprises Index (H-share index) futures contracts on March 31.