The Sensex at the Bombay Stock Exchange fell 53 points, or 0.3 percent, to 18,580, on fag-end selling in blue-chips, amid the monthly expiry in the derivatives segment, on Thursday. The Nifty at the National Stock Exchange dropped 14 points, or 0.3 percent, to 5,650.But stock markets in Japan, China, Hong Kong, South Korea and Singapore rose between 0.5 percent and 2.5 percent.