Sensex on Monday dropped 306.01 points to close at 55,766.22 while Nifty dropped 88.45 points to close at 16,631. Both indices broke their six-day gaining streak on Monday. Mahindra and Mahindra was the worst performing Sensex stock, down 3.83%, followed by Reliance Industries and Maruti Suzuki India. Tata Steel rose 3.1% as the top gainer, accompanied by IndusInd Bank.