The rupee depreciated 4 paise to 78.17 against the US dollar in opening trade on Wednesday, tracking a muted trend in the domestic equity market and a firm American dollar.

However, lower crude prices in the international market supported the local unit and restricted its fall, forex dealers said.

At the interbank foreign exchange, the rupee opened unchanged at 78.13 against the US dollar, then inched lower to quote 78.17, registering a decline of 4 paise over the last close.

In the previous session, the rupee had closed at 78.13 against the US dollar.

On the domestic equity market front, the 30-share Sensex was trading 364.12 points or 0.69 per cent lower at 52,167.95, while the broader NSE Nifty fell 123.10 points or 0.79 per cent to 15,515.70.

Meanwhile, the dollar index, which gauges the greenback's strength against a basket of six currencies, rose 0.17 per cent to 104.61.

Global oil benchmark Brent crude futures slumped 3.47 per cent to USD 110.67 per barrel.

Foreign institutional investors remained net sellers in the capital market on Tuesday as they offloaded shares worth Rs 2,701.21 crore, as per exchange data.