The Bombay Stock Exchange benchmark Sensex plummeted by over 300 points in opening trade on Monday. This follows panicky fund managers and retail investors giving into selling pressure for the fourth consecutive session, prompted by weak global cues amid concerns over the unrest in Egypt. The 30-share barometer fell to 18,094 points in the first few minutes of trade on Monday. The Sensex had lost 755 points in the previous three sessions. Similarly, the wide-based National Stock Exchange Nifty index declined by 80 points to 5,432.60. In other Asian markets, Japan's Nikkei was down by 1.63 per cent, while Hong Kong's Hang Seng index was down by 1.20 per cent. The US Dow Jones Industrial Average ended 1.39 per cent lower on Friday.