A TUMBLING Tokyo market and fears that Governor Chris Patten will risk China's wrath by pressing ahead with democratic reform combined yesterday to send Hong Kong stocks plunging more than 240 points. The Hang Seng index dived 310.56 points or 3.35 per cent to 8,963.86 in mid-morning trading. Afternoon trading saw a modest recovery as bargain hunters moved in, leaving the market to close at 9,012.77. In the territory, uncertainty was rife after the 17th round of Sino-British talks in Beijing on the territory's political future ended on Saturday without agreement. In Tokyo, stocks closed above 16,000 yesterday after slumping 1,000 points earlier in the day. As Hong Kong futures plunged, the exchange unveiled a series of housekeeping measures to keep contracts in line with market activity. Big swings have prompted the authorities to lift the maximum fluctuation to 500 points from 300 points. From today, strike prices on Hang Seng Index options are to be set at staggered intervals, depending on the level of the index. With the index above 8,000 they are to be set at 200 index points.