U.S. stock index futures firmed on Friday at the end of a volatile week marred by worries about rising inflation and a subsequent tightening of monetary policy, while investors awaited retail sales data. Retail sales is likely to have increase 1% in April after a 9.8% jump in March, data at 8:30 a.m. ET is expected to show. Industrial production and consumer sentiment data will also be released later in the day.
