The Bombay Stock Exchange Sensex fell by 516.06 points on Tuesday and dropped below the 25,000-mark after the Reserve Bank lowered the repo rate by 25 basis points to 6.5%, which PTI said was in line with market expectations. The repo rate is the one at which the RBI lends to commercial banks. The National Stock Exchange Nifty50 index also posted a 155-point drop to settle at 7,603.20. Real estate, banking, automotive and rate-sensitive stocks were among the worst hit by the slump. The rupee also fell by 29 paise to Rs 66.50 against the dollar in intra-day trading.