Falling for the third straight session, the Sensex at the Bombay Stock Exchange declined 49 points, or 0.3 percent, to close at a fresh one-week low of 20,062, on Wednesday. The Nifty at the National Stock Exchange fell 20 points, or 0.3 percent, to 6,095.Stock markets in Japan, China, Hong Kong, Singapore, and South Korea again ended mixed.