New Delhi, After rising marginally in the opening session, India's key indices -- S&P BSE Sensex and NSE Nifty50 -- declined in the afternoon session on Thursday.

At 1.08 a.m., Sensex was 0.5 per cent or 259 points down at 55,209 points, whereas Nifty was down 0.5 per cent or 82 points at 16,523 points.

Among stocks, Tech Mahindra, Asian Paints, HDFC Life, Dr Reddy's, and Shree Cement were the top five losers in the afternoon session, down 4.8 per cent, 4.7 per cent, 3.6 per cent, 2.9 per cent, and 2.9 per cent, respectively.

On the sectoral indices front, Nifty auto and consumer durables traded deep in the red, data showed.

Coal India, Wipro, Power Grid Corporation of India, Tech Mahindra, and HCL Technologies, on the other hand, were the top five gainers, NSE data showed.