Stock markets in the United States and Europe retreated last week as the number of new COVID-19 cases increased steadily in America. On Thursday, there were more than 44,000 new cases, the highest daily total to date, according to data from the Centers for Disease Control. “The turn has created a new puzzle for investors, many of whom had started focusing on 2021 earnings expectations as the next performance-driver for stocks. The old market gauges, like manufacturing surveys, jobs tallies, and retail sales, feel like lagging indicators. The new leading indicators deal with the disease. Yet tracking its progress is tricky even for epidemiologists who have studied these issues for decades,” reported Avi Salzman of Barron’s.