The Central Bank of Nigeria (CBN) said on Monday that it sold 221.57 million dollars (N3.4 billion) worth of foreign exchange at its 30th bi-monthly Wholesale Dutch Auction System (WDAS). The apex bank disclosed this on its Website, released after the WDAS trading. The volume of the forex sold dropped by 78.43 million dollars (N125.6 million), against the 300 million dollars sold on July 29. The naira maintained its appreciation against the dollar at the auction, trading at N155.75 to the dollar. The exchange rate was N155.75 to a dollar, compared with the N155.76 at the auction on July 29. The report added that 18 banks participated at the bi-weekly WDAS auction.