Falling for the third straight session, benchmark Sensex slipped over 97 points in see-saw trade on Friday to close at 36,227.14, led by losses in L&T and Yes Bank.
Besides, caution prevailed ahead of RBI policy meeting next week, brokers said.
Selling took hold at the start of October futures and options (F&O) series in the derivatives segment as investors were concerned over the surging crude oil prices and escalating trade tensions between the US and China, they added.
The 30-share Sensex closed lower by 97.03 points, or 0.27 per cent, at 36,227.14 after shuttling between 36,551.86 and 35,985.63.
It had lost 327.89 points in the previous two sessions.
Also, the NSE Nifty shed 47.10 points, or 0.43 per cent, to finish at 10,930.45. During the session, it moved between 11,034.10 and 10,850.30.
Both the indices recorded their fourth straight weekly fall. The Sensex lost 614.46 points, or 1.67 per cent and the Nifty dropped 212.65 points, or 1.91 per cent, this week.
Meanwhile, domestic institutional investors (DIIs) sold shares worth a net Rs 186.69 crore, while foreign portfolio investors (FPIs) bought shares worth Rs 552.44 crore Thursday, according to provisional data.