Mumbai, Nov. 12 -- The domestic equity benchmarks traded with significant gains in the early-afternoon trade, supported by optimism over a potential trade agreement with the U.S. and the reopening of the American government. Investor sentiment was further buoyed after Bihar exit polls indicated a likely victory for the incumbent NDA alliance.

The Nifty traded above the 25,900 level. Oil & gas shares advanced after declining in the past three consecutive trading sessions.

At 12:30 ST, the barometer index, the S&P BSE Sensex, zoomed 685.17 points or 0.82% to 84,556.49. The Nifty 50 index surged 208 points or 0.81% to 25,903.50.

In the broader market, the S&P BSE Mid-Cap index rose 0.36% and the S&P BSE Small-Cap index added 0.69%.

The m...