U.S. stock index futures were muted on Thursday as Nvidia's stellar quarterly results garnered a lukewarm response from investors and downbeat earnings from software company Salesforce weighed on ‌sentiment. Nvidia inched 0.6% higher in premarket trading after the chipmaker posted better-than-expected results for the January quarter ‌and forecast current-quarter revenue above market estimates. "The needle has clearly shifted when it comes to what its going to take to convince investors ​that the billions being poured into AI infrastructure will pay off," said Raffi Boyadjian, lead market analyst at Trading Point.