The Sensex at the Bombay Stock Exchange fell 155 points, or 0.8 per cent, to 18,283 in opening trade, today, on profit-booking by investors, and a negative trend on the other key Asian bourses. After paring its losses, somewhat, the Sensex still stood 96 points, or 0.5 percent in the red, at 18,342, in afternoon trading a short while ago. Other regional stock markets in Japan, China, Hong Kong, Indonesia, South Korea, Singapore and Taiwan were down by between 1.2 percent and 2.2 percent, on concerns over political tensions in West Asia.