The BSE Sensex slumped 0.68 per cent in the last two weeks to 58,840 on September 16 whereas the Nifty 50 index closed at 17,530.85 points. Meanwhile, the Small-Cap index surged by 0.49 per cent to 29,199.39 and the Mid-Cap index declined by 0.09 per cent to 25,558.21.