Wholesale prices in April posted their highest annual increase in more than three years, signaling more nettlesome inflation as pipeline costs intensify.The producer price index rose a seasonally adjusted 1.4% for the month, much higher than the 0.5% Dow Jones consensus forecast and the upwardly revised 0.7% March increase, the Bureau of Labor Statistics reported Wednesday. This was the largest monthly gain since March 2022.On an annual basis, the index was up 6%, the biggest increase since December 2022.