Mumbai, Aug. 4 -- The Indian benchmark indices opened on a muted on Tuesday with Sensex and Nifty opening with a gap-down, erasing gains from Monday's bull run. Sensex opened at 79,132.97 as against previous close of 78,639.03 while Nifty opened at 24,703.90 as against 24,774.30 following the introduction of a new Closing Auction Session (CAS) framework.

CAS, which was implemented on Monday, pools all buy and sell orders at the end of the trading day and identifies a single price at which the maximum number of shares can be traded. This price is then set as the stock's closing price.

Sensex was trading at around 78,707.73, up 68.70 points or 0.09 per cent while Nifty was trading at around 24,594.60, down 179.70 points or 0.73 per cent a...