In the just ended October-December quarter, the company said it booked a small loss of 600 million yen, down from a 15.9 billion net profit a year ago. Revenues tumbled 40 percent to 512.4 billion yen. Mazda's biggest market is the U.S., where sales are plunging as some consumers cut back on new purchases and others are unable to buy because of tightening credit conditions. The cars it does sell generate less profit because the strong yen means that sales abroad are worth less when converted back into yen. The company also said rising material costs are hurting its bottom line. In a breakdown of its quarterly operating profit, which reflects core business performance but excludes taxes, dividends, asset sales and other items, the company said the strengthening yen chopped off 42 billion yen, while declining sales cut 34.1 billion yen. That helped weigh Mazda down to an operating loss of 24.2 billion yen for the quarter, versus a 35.3 billion profit a year earlier. Like other carmakers, Mazda has seen its sales in the U.S. plummet in recent months. The company said Tuesday its sales in the country fell 27.3 percent in January from a year earlier. Competitors General Motors Corp., Ford Motor Co., Toyota Motor Corp. and Honda Motor Co. have also reported big sales declines. The industry as a whole has reported at least a 30 percent fall in U.S. sales in each month since October. Mazda has close ties with U.S. carmaker Ford, which helped turn around its business decades ago, sending executives and sharing technology and auto parts to cut costs. Struggling under massive losses, Ford in November said it would sell the majority of its 33.4 percent stake in the Japanese carmaker, although the two would continue to work closely together.