Equity benchmark indices Sensex and Nifty opened in the red on Thursday. BSE Sensex started the trading session 243.57 points, or 0.31%, lower at 77,319.33, whereas the Nifty opened at 23,909.05. The decline comes a day after both indices jumped higher on the announcement of ceasefire between Iran and US. However, investors' sentiment turned cautious over the durability of ceasefire.