Mumbai: The BSE benchmark, Sensex, gained for the fourth straight day on Thursday, up 111 points, led by the auto sector amid a firm trend in global markets. Sensex, which had gained nearly 300 points in last three trading sessions, advanced further by 111.32 points or 0.64 percent to 17,503.71. The NSE index, Nifty, rose 32.40 points or 0.61 percent to 5,332.40. Brokers said there was sustained buying in interest- sensitive stocks since Tuesday's cut in lending rates by the Reserve Bank. The move has led to interest rate cuts by banks such as PNB and IDBI bank. They also said that higher openings in the European markets amid easing worries about the euro-zone debt crisis, further supported the uptrend. Besides, investor picked up stocks ahead of the results to be announced by market heavyweight Reliance Industries. The auto sector index gained 2.05 percent to 10,744.73 as the sector remained in demand. Infosys, which had lost about 16 percent in the past couple of sessions after weak revenue outlook for this fiscal, gained 1.31 percent on value buying. Tata Motors, Maruti Suzuki, Bajaj Auto, Hero MotoCorp, Coal India, HDFC Bank, M&M, TCS were other major gainers. Of the 30 Sensex stocks, 21 gained, 8 declined while DLF ended unchanged.