The Sensex at the Bombay Stock Exchange dropped 121 points, or 0.8 percent, to again close below the 16,000 mark, at 15,881, today, amid a falling rupee, and weak global markets. The Nifty at the National Stock Exchange fell 37 points, or 0.8 percent, to 4,763. Stock markets in Japan, China, Hong Kong, South Korea and Singapore dropped between 0.3 percent and 0.9 percent.