The Indian equity benchmarks staged a gap down opening on Friday dragged by weakness in banking and information technology shares amid weak cues from global markets. The Sensex fell as much as 478 points and Nifty 50 index touched an intraday low of 18,120. Meanwhile, other Asian markets were also trading lower with Japan's Nikkei dropped 1.68 per cent, Hong Kong's Hang Seng declined 1 per cent and China's Shanghai Composite fell 0.6 per cent.