The rupee was trading weak at 66.51 in the evening session on increased dollar demand from banks and importers.
Dealers said a firm dollar against some global currencies overseas and a weak domestic equity market weighed on the rupee sentiment.
The rupee depreciated by 9 paise to quote at 66.49 against the dollar at the Inter-bank Foreign Exchange (forex) market in early trade.
It hovered in a range of 66.60 and 66.46 before quoting at 66.51, down 11 paise at 4.40 pm local time.
In the overseas market, the yen hit a two-week low against the dollar on Friday after a media report said that the Bank of Japan could expand its negative interest rate policy beyond its current applications.
The BoJ is considering applying negative rates to its lending programme for financial institutions, Bloomberg reported on its Web site on Friday.
The rupee had dropped by 18 paise to end at 66.40 yesterday on fresh demand for the US dollar from banks and importers despite weakness in the greenback overseas.
Meanwhile, the Sensex ended down by 42.24 points or 0.16 per cent at 25,838.14.