The BSE benchmark Sensex tumbled over 440 points and the NSE Nifty cracked below the key 15,000-level in early trade on Friday in line with a slump in other Asian markets as US bond market turmoil continued to fan investor worries globally. The BSE gauge Sensex was trading at 50,405.99, showing a drop of 440.09 points or 0.87 per cent in the opening session. Similarly, the NSE barometer Nifty was quoted lower by 124.75 points or 0.83 per cent at 14,956
