Fears over the Delta variant—and new COVID surges across the U.S.—has rattled the stock market, leading to Wall Street’s worst day in months. On Monday, the S&P 500 dropped 1.6 percent and the Stoxx Europe 600 plummeted by 2.3 percent, some of the biggest declines seen this year. Both Norwegian Cruise Line and United Airlines fell 5.5 percent, as travel and tourism are at risk of being restricted once again as a result of the rise in COVID infections. The United States is currently averaging over 31,000 cases a day and some cities are going back to mask mandates in public spaces. Around the world, cases are rising fast as well. On Monday, Singapore announced it was facing the highest levels of infection it’s experienced in nearly a year. In Japan, where the Tokyo Olympic Games are scheduled to begin in a few days, a number of athletes, coaches, and referees have already tested positive for the virus.