Shares of air carriers took a deep dive in premarket trading Thursday, as Russia's invasion of Ukraine weighed heavily on travel-related stocks. The U.S. Global Jets ETF JETS, -3.21% sank 5.1% toward a two-month low, as futures ES00, -2.47% for the S&P 500 SPX, -1.84% slumped 2.4% toward a nine-month low.