U.S. consumer prices have soared above economists’ predictions and by the most in over a decade, as fiscal stimulus and booming demand pushed against supply constraints, potentially fueling market fears of a prolonged bout of higher inflation. The year-over-year consumer price index (CPI) jumped by 4.2 percent in April after rising 2.6 percent in March, the Labor Department said in a release on Wednesday (pdf). This is the largest 12-month increase since September 2008, when the index rose by 4.9 percent. Forecasts from economists polled by DailyFX, a financial market insights platform, expected the year-over-year inflation measure to come in at 3.6 percent, compared to the actual 13-year high. On a monthly basis, the CPI inflation measure jumped 0.8 percent in April after rising 0.6 percent in March, while the so-called core CPI, which excludes the volatile food and energy components, soared by 0.9 percent. The surge in the core CPI is the …