The Sensex at the Bombay Stock Exchange dropped 48 points, or 0.3 percent, to 18,154, on profit-booking by investors, amid falling global markets on Thursday.The Sensex had gained more than 450 points in the previous three trading sessions.The Nifty at the National Stock Exchange declined 10 points, or 0.2 percent, to 5,522.Stock markets in Japan, China, Hong Kong, Singapore and South Korea lost between 0.2 percent and 1.4 percent, after a delay in the decision on a bailout for Greece.