US stock index futures jumped on Wednesday as signs of a working COVID-19 vaccine raised hopes of a faster-than-expected economic rebound even as some states braced for new business restrictions to combat surging infections. Nasdaq 100 futures were up more than 1% after underperforming this week, with technology mega-caps including Netflix Inc, Amazon.com Inc and Facebook Inc, the so-called stay-at-home stocks, gaining about 1% in premarket trading. Encouraging data from a late-stage vaccine earlier this week prompted a rotation away from stay-at-home beneficiaries, such as technology shares, and lifted demand for stocks sensitive to economic growth, as well as those that have lagged this year including energy, financials and industrials. The top U.S. infectious disease specialist urged caution until a vaccine can be approved and distributed, as California and several states across the U.S. Midwest tightened restrictions for residents. Markets also got a boost after Democrat Joe Biden was projected the winner of the U.S. election on Saturday. While President Donald Trump pursues a flurry of lawsuits challenging the results, legal experts say the litigation has little chance of changing the outcome. At 06:39 a.m. ET, Dow E-minis were up 0.78% and S&P E-minis gained 0.85%. Lyft Inc jumped 5.5% after the ride-hailing app said it was working on a new service to take a slice of the burgeoning food-delivery market, as it works to make up for a drop in quarterly revenue.