Domestic equity benchmark Sensex tumbled over 300 points in opening session on August 3 tracking losses in index-heavyweights Reliance Industries and HDFC twins amid weak cues from global equities.

The BSE Sensex was trading 303.74 points or 0.81% lower at 37,303.15; while the NSE Nifty was down 77.15 points or 0.70% at 10,996.30.

Kotak Bank was the top loser in the Sensex pack, falling around 3%, followed by IndusInd Bank, HDFC Bank, ONGC, PowerGrid, Axis Bank, Sun Pharma and Reliance Industries (RIL).

On the other hand, Bajaj Auto, Titan, Maruti, M&M and SBI were among the gainers.

In the previous session, the 30-share Sensex ended 129.18 points or 0.34% lower at 37,606.89, while the NSE Nifty fell 28.70 points or 0.26% to 11,073.45.

Exchange data showed that foreign institutional investors sold equities worth ₹958.64 crore on a net basis on July 31.

According to traders, selling in index majors RIL and HDFC duo dragged key indices lower.

Further, foreign fund outflow, concerns over rise in COVID-19 cases across the world kept investors cautious, they added.

The number of cases around the world linked to COVID-19 has crossed 1.8 crore, while the infection count in India crossed 18 lakh.

Bourses in Hong Kong and Seoul were in the red, while Shanghai and Tokyo were trading on the positive territory.

Global oil benchmark Brent crude was trading 0.55% lower at $43.28 per barrel.