The BSE benchmark Sensex gained over 51 points to 18,875 in early trade today on sustained buying by funds and retailers on expectations of more policy reforms by the government amid a firming trend in Asian region. The index has gained nearly 245 points in the previous two trading sessions. The markets were closed yesterday on account of 'Gandhi Jayanti'. In Asian region, Hong Kong's Hang Seng rose by 0.67 per cent, while the Japan's Nikkei by 0.10 per cent in early trade today. The US Dow Jones Industrial Average, however, had ended 0.24 per cent lower in yesterday's trade.