U.S. stock index futures struggled for direction on Wednesday, cooling off after a day-earlier rally, as worries lingered about the new Omicron variant of the coronavirus and its impact on global economic recovery. Wall Street’s main indexes ended with hefty gains on Tuesday, but few market-moving catalysts and thin volumes in the last two weeks of trading this year are seen aiding higher volatility. The S&P 500 index is up roughly 24 percent in 2021. Investors looked for updates on the Omicron variant after Germany, Scotland, Ireland, Portugal, the Netherlands, and South Korea re-imposed lockdowns or other curbs. Most big technology stocks fell in premarket trading. Apple Inc., Amazon.com Inc., Meta Platforms, and Alphabet Inc. dropped between 0.1 percent and 0.4 percent. Tesla Inc gained 2.7 percent, bucking a trend among its megacap peers. According to an interview released on Tuesday, Tesla CEO Elon Musk said he had sold “enough …