Indian stock market indices extended their losses from the previous week, though marginally, tracking weak US market cues and concerns of over-heating in small and midcaps space. At 9.19 am, soon after the opening bell, Sensex was at 72,585.93, down 57.50 points or 0.079 per cent, Nifty was at 21,991.85 points, down 31.50 points or 0.14 per cent. Among the widely tracked Nifty 50 stocks, 21 advanced and the rest 29 declined at the time of filing this report.