Falling for the third straight session, the Sensex at the Bombay Stock Exchange on Monday dropped 193 points, or 1.1 percent to 17,273 on continued selling by funds, amid weak European markets. The Sensex had lost over 450 points in the previous two trading sessions. The Nifty at the National Stock Exchange fell 61 points, or 1.1 percent, to 5,257.Stock markets in Japan, China, Hong Kong, South Korea and Singapore ended mixed.