The rupee on Friday plunged by 37 paise against the US dollar as investors turned cautious in view of massive selloffs in domestic equities and worries over a new variant of Covid-19.

At the interbank foreign exchange market, the local currency opened at 74.60 and witnessed an intra-day high of 74.58 and a low of 74.92 against the US dollar in day trade.

The local unit settled at 74.89 a dollar, down 37 paise over its previous close of 74.52.

The dollar index, which gauges the greenback's strength against a basket of six currencies, was trading 0.34 per cent down at 96.44.

"Rupee erased all the gains of the month following risk-off moods after worries over a new variant of Covid-19 surges. Month-end dollar demand and unwinding of carry trade in global forex markets also weighed on rupee," Dilip Parmar, Research Analyst, HDFC Securities.

The rupee registered its biggest weekly fall after October 8, and closed at its weakest level since November 2, Parmar said.