Traders said some bureau de change operators have been finding it difficult to access their forex account and get dollar supply.
On Thursday, the naira had closed at 409 per dollar on the parallel market. On the inter-bank market, it traded at 315 compared with 305 the previous day.
Shares in some of the banks dropped by up to 7.8 percent.
Bank executives have been meeting central bank officials to resolve the forex issue as investors continued to dump their shares second day.
On the inter-bank market, the currency gained 0.2 percent to close at 305 naira to the greenback with traders attributing the rise to central bank dollar sale to prop up the unit.
It would be recalled that also during the week, the CBN settled $152.48 million of naira futures contracts it sold in June at an exchange rate of 279 naira per dollar, further draining its reserves, which is at its lowest in more than 11 years.