A measure of producer prices declined for a second consecutive month in August as fuel costs continued to drop, though an underlying measure of wholesale costs firmed in a sign of persistent inflation. The producer price index for final demand edged down 0.1% from a month earlier and rose 8.7% from a year ago, according to the U.S. Department of Labor. Excluding the energy and food components, the core PPI rose a bigger-than-forecast 0.4% in August and was up 7.3% from a year ago.

Goods prices declined 1.2% as gasoline prices continued to drop. Food prices were unchanged from the previous month. Excluding energy and food, the index of goods costs advanced 0.2% for a second month. Services prices rose 0.4%, the most in three months. Forty percent of the increase was because of higher margins for fuel retailers.

Meanwhile, a potential railway strike threatens to hinder supply chains. The walkout, which could start later this week, would disrupt the transportation of goods ranging from food and lumber to coal.