The Sensex resumed lower at 20,228.76 and hovered in a range of 20,211.79 and 20,323.77 before quoting at 20,254.16 at 1030 hrs, showing a marginal gain of 4.90 points or 0.02 per cent from its last close.
The NSE 50-share Nifty also moved up by 7.90 points or 0.13 per cent to 6,015.35 at 1030 hrs.
Major gainers were Jindal Steel (2.06 per cent), SSLT (2.06 per cent), Tata Steel (1.72 per cent), Maruti (1.26 per cent), Hero Motocorp (1.24 per cent), Cipla (1.22 per cent), Hindalco (1.13 per cent) and Tata Motors (1.06 per cent).
Tata Steel extended Wednesday's gains triggered by the company's announcement of increase in production and sales deliveries of steel in Q2 of 2013.
Foreign institutional investors (FIIs) bought shares worth a net Rs 326.58 crore yesterday as per provisional data from the stock exchanges.
Asian markets were trading mixed in their early trade. Key benchmark indices in Singapore, Japan and Indonesia rose by 0.44 per cent to 0.77 per cent while indices in China, Hong Kong and South Korea fell by 0.01 per cent to 0.88 per cent.