Snapping a three-day rally, the Sensex at the Bombay Stock Exchange closed 45 points, or 0.2 percent lower, at 20,016, on profit-booking, amid subdued Asian and European markets, today. The Nifty at the National Stock Exchange shed 16 points, or 0.3 percent, to 5,984.Stock markets in Japan, China, Hong Kong, South Korea and Singapore ended mixed.