The Sensex gained for the third day today, as the follow-up buying continued after the budget. Positive Asian markets helped boost the sentiment further. The Sensex closed at 17,000 mark, up by 227 points.The National Stock Exchange Nifty gained 71 points to finish at 5,088. The rally in the Indian markets was led by realty and oil and gas stocks that had under performed in the last two sessions.Strong buying was also seen in power, FMCG and banking stocks. Market heavyweight RIL rallied nearly 4 per cent. The other major gainers included JP Asso, Tata Power, NTPC and M&M. Outside the Sensex stocks, Gail closed higher by around 1.7 per cent while Essar Oil closed higher by around 1 per cent.