Share prices closed lower Monday after a day of choppy trading on the London Stock Exchange. The Financial Times-Stock Exchange 100-share index fell 8.4 points, or 0.5 percent, to 1,794.3. Trading volume was moderate at 479.3 million shares, compared with the 708.7 million shares traded Friday. The market sank at the onset of trading, reflecting concerns about how the administration of President-elect George Bush would handle U.S. economic problems. But it rose sharply by midday on bargain-hunting by big investors, only to sink on the release of disappointing British economic statistics. The Financial Times 30-share index fell 8.7 points to 1,452.5. The Financial Times 500-share index fell 6.68 points to close at 1,021.95.