Markets opened on a weak note on Monday, with the Nifty 50 slipping 66.85 points or 0.27 per cent to 24,299.15 and the Sensex falling 305.23 points or 0.39 per cent to 77,704.02, as elevated crude oil prices and Middle East tensions continued to dampen investor mood.The Nifty had closed Friday's session at 24,366 while the Sensex ended at 78,009.25. Both indices opened lower, Nifty at 24,343.45 and Sensex at 77,892.92, before sliding further in early trade.Brent crude held near $88.6 a barrel, having risen ...