Mumbai, April 17 -- The key equity indices traded with major gains in the afternoon trade, buoyed by positive global cues and sustained inflows from foreign institutional investors. The Nifty hovered above the 23,800 level. PSU bank shares extended gains for the fourth consecutive trading session. The weekly Nifty50 F&O contracts are set to expire today.

At 14:28 IST, the barometer index, the S&P BSE Sensex, surged 1,440.81 points or 1.87% to 78,485.10. The Nifty 50 index jumped 395.85 points or 1.69%, to 23,833.60.

The broader market underperformed the frontline indices. The S&P BSE Mid-Cap index advanced 0.54%, and the S&P BSE Small-Cap index rose 0.59%.

The market breadth was strong. On the BSE, 2,415 shares rose and 1,464 shares fe...