Snapping its three-session winning streak, the Sensex at the Bombay Stock Exchange slipped 80 points, to 16,631 in opening trade on Friday, on profit-booking and weak Asian markets. Remaining in the red, the Sensex stood 48 points, or 0.3 percent lower, at 16,663, a short while ago. Key stock indices in Hong Kong, Japan and Singapore were down by between 0.3 percent and 0.9 percent.