Falling for the third straight session, the Sensex at the Bombay Stock Exchange lost 151 points, to slip below the 20,000-level, at 19,975, in early trade, today, on profit-booking by investors. Remaining weak, the Sensex stood 130 points, or 0.7 percent in the red, at 19,995 a short while ago.Also, today, both the Bombay Stock Exchange and the National Stock Exchange introduced a 15-minute, pre-open session Call Auction, which is expected to reduce volatility. Meanwhile, other key Asian stock markets in Japan, China, South Korea, Singapore, Taiwan, Indonesia and Hong Kong were down by between 0.1 percent, and 1.8 percent, today, as investors took some profits ahead of a widely expected easing in US monetary policy.