Falling for the fourth straight session, the Sensex at the Bombay Stock Exchange declined 64 points, or 0.3 percent, to close at 20,787, amid weak regional markets, today. The Sensex has now lost over 380 points in four trading sessions. The Nifty at the National Stock Exchange fell 20 points, or 0.3 percent, to 6,191. Stock markets in Japan, China, Hong Kong and Singapore declined between 0.2 percent and 2.4 percent.