Falling for the sixth straight session, the Sensex at the Bombay Stock Exchange lost 59 points, or 0.3 percent, to close at a one-and-a-half month low of 19,580, after a lower GDP growth forecast, and amid declining Asian markets, today. The Sensex has now declined 425 points in the last six trading sessions. The Nifty at the National Stock Exchange fell 20 points, or 0.3 percent, to 5,939.Stock markets in Japan, China, Hong Kong, South Korea and Singapore lost between 0.2 percent and 0.9 percent.