Stocks in Tokyo fell in Wednesday morning trading on weak US economic data and a downgrade in Japan's sovereign credit rating by Moody's Investors Service. The benchmark Nikkei 225 Stock Average fell 93.4 points, or 1.1 per cent, to trade at 8,639.61 while the broader-based Topix index was down 8.15 points, or 1.1 per cent, at 742.24, according to a report of the German Press Agency "DPA".