Mumbai (Maharashtra) [India], September 21 (ANI): Indian benchmark indices opened higher on Monday despite muted cues from GIFT Nifty, as easing oil prices supported sentiment, with the Sensex gaining over 400 points and the Nifty holding above 23,360. Sensex opened at 74,535.18 and was trading at around 74,718.49, up 423.53 points or 0.57% against the previous close of 74,294.96 at around 9:27 AM. Nifty opened a