Shares fell sharply Thursday on the Seoul stock exchange on heavy selling by institutional and foreign investors, DPA reported. The benchmark Kospi index fell 43.21 points, or 2.6 per cent, to close at 1,615.62. Declining issues outnumbered advancers 588 to 205. The main index of the technology-heavy Kosdaq market plunged 9.48 points to 621.81 The US dollar was quoted at 982.40 won, after 971.30 won on Wednesday.