MUMBAI: A steep fall in auto and rate-sensitive stocks cut short the BSE benchmark Sensex’s three-day gaining streak on Monday, with the 30-share index shedding 111 points amid fears of an RBI rate hike on Tuesday.   Nevertheless, the Bombay Stock Exchange barometer managed to end above the psychological 18,000-level at 18,020.05, down 110.93 points, or 0.61 per cent. The wide-based 50-share Nifty index of the National Stock Exchange, too, finished 0.64 per cent down at 5,414.30.