Indian stock markets opened in the green on Friday, with both benchmark indices witnessing modest gains despite continued foreign portfolio investor (FPI) outflows. The Nifty 50 index was trading at 25,433.95, up by 28.65 points or 0.11 per cent, while the BSE Sensex stood at 83,340.22, gaining 100.75 points or 0.12 per cent in the opening session.