Producer prices see largest increase in over a year E-mail Tweet Facebook Google Plus Linkedin Share icons by John Kell @FortuneMagazine May 14, 2014, 10:18 AM EDT FORTUNE — U.S. producer prices saw their largest increase in over a year last month, hinting at some inflation pressures at the wholesale level. The Labor Department said its seasonally adjusted producer price index (PPI) for final demand advanced 0.6 percent in April, marking the biggest rise since September 2012. It was the second consecutive month that metric advanced. In March, the index increased 0.5 percent. The Department of Labor’s PPI measures a change in selling prices received by domestic producers. The price index for foods reported the largest increase last month, while energy and transportation and warehousing prices also rose. Lately, there have been conflicting reports about the strength of the U.S. economy. U.S. employers continue to add jobs, which can help lift consumer discretionary spending. And the National Federation of Independent Business this week reported optimism among small business owners has reached a post-recession high. But earlier this week, the Commerce Department reported retail sales grew a less-than-expected 0.1% in April from the prior month.