Indian stock market indices were marginally lower at opening bell Friday, largely due to more-than-expected inflation in the US and related weak cues. At 9.21 am, Sensex was at 74,859.00 points, down 179.15 points or 0.24 per cent, while Nifty was at 22,701.80 points, down 52.00 points or 0.23 per cent. Among the widely-tracked Nifty 50 stocks, 15 advanced, 34 declined, and one was unchanged, NSE data showed.