Mumbai, July 28 -- The key equity barometers traded with modest gains in the early afternoon trade as investors remained cautious ahead of the U.S. Federal Reserve's policy decision and continued to assess the ongoing corporate earnings season. Market sentiment remained volatile due to the weekly expiry of Nifty 50 derivatives contracts, leading to heightened intraday swings. The Nifty traded a tad above the 24,000 level. Auto shares extended their gains for the second consecutive trading session.

At 12:30 IST, the barometer index, the S&P BSE Sensex, added 87.85 points or 0.11% to 76,923.63. The Nifty 50 index rallied 24.05 points or 0.10% to 24,017.95.

The broader market underperformed the frontline indices. The BSE 150 MidCap Index s...