Indian stock markets, including the BSE Sensex and NSE Nifty50, opened lower on Friday, resuming trading after the Christmas holiday. The Sensex fell over 130 points, and the Nifty tested 26,100. This follows a marginal decline on Wednesday, with analysts noting cautious sentiment and subdued trading activity due to thin volumes. The Nifty's short-term outlook remains cautious unless it reclaims the 26,200 level.