Falling for the second straight day, the Sensex at the Bombay Stock Exchange dropped 67 points to a fresh four-month low of 16,480, Wednesday, on continued selling by investors, amid weak global markets. The Nifty at the National Stock Exchange declined 25 points to 4,975. Key stock indices in Japan, China, Hong Kong, Singapore and South Korea lost between 0.8 percent and 1.7 percent.