US stock futures fell on Friday as FedEx issued an ominous warning about the global economy, adding to concerns that solid US data would give the Federal Reserve ammunition to continue raising interest rates aggressively. Dow futures fell 0.5%, S&P 500 futures lost 0.6% and Nasdaq 100 futures dropped 0.7%. In extended trading, FedEx plunged 16% after withdrawing its full-year guidance and announcing that it will aggressively accelerate cost reduction efforts, citing macroeconomic trends that “significantly worsened.” In regular trading on Thursday, the Dow lost 0.56%, the S&P 500 dropped 1.13% and the Nasdaq Composite tumbled 1.43%, with all three benchmarks on track to notch their fourth losing week in five. Better-than-expected retail sales data and jobless claims numbers, on top of a surprisingly hot August CPI report, fueled expectations that the Federal Reserve will need to step up its fight against inflation.