Indian stock markets opened flat on Wednesday ahead of the much-awaited U.S. Federal Reserve meeting, even as Asian markets rallied on hopes of a rate cut. The Nifty 50 index opened at 25,982, up 45.80 points or 0.18 per cent, while the BSE Sensex started the session at 84,654.44, gaining 26.28 points or 0.03 per cent.