The Sensex at the Bombay Stock Exchange dropped 129 points, or 0.7 percent, to 17,489, on profit-booking, amid below-average monsoon concerns, and subdued global markets, on Wednesday. The Nifty at the National Stock Exchange fell 39 points, or 0.7 percent, to 5,306. Stock markets in Japan, China, Hong Kong, South Korea and Singapore ended mixed.