U.S. stock index futures edged lower on Thursday as IBM and Tesla fell after their quarterly results, with investors awaiting more reports to see the impact of supply chain disruption and labor shortages on companies. Tesla Inc. fell 1 percent in premarket trading as it said on Wednesday its upcoming factories and supply-chain headwinds would put pressure on its margins after it beat Wall Street expectations for third-quarter revenue. The EV maker’s quarterly report comes a day after shares of growth peer Netflix Inc. slipped following its results. Other mega-cap stocks including Facebook Inc., Apple Inc., and Amazon.com Inc. fell between 0.1 percent and 0.3 percent on Thursday. IBM slipped 4.7 percent after it missed market estimates for quarterly revenue as its managed infrastructure business suffered from a decline in orders. Investors are keeping a close eye on growth outlook from companies facing rising costs, labor shortages, and supply chain …