Falling for the second straight session, the Sensex at the Bombay Stock Exchange declined 80 points, or 0.4 percent, to close at 20,895, on profit-booking by investors, amid weak regional bourses, on Wednesday. The Nifty at the National Stock Exchange fell 38 points, or 0.6 percent, to 6,215.Stock markets in China, Hong Kong, South Korea and Singapore all ended lower.