Snapping its four-day upward march, the Sensex at the Bombay Stock Exchange fell 34 points, or 0.2 per cent, to 17,936, in opening trade, today, on profit booking by investors, amid weak global cues. Falling further, the Sensex stood 138 points, or 0.8 percent in the red, at 17,832, a short while ago. Other Asian markets in Japan, China, Hong Kong, Singapore, Taiwan and Indonesia were down between 0.2 percent and 1.5 percent, today. The US Dow Jones Industrial Average had lost 0.7 per cent, overnight.