An 800-Year-Old Math Principle May Help Find Bottom to S&P 500’s Rout

The S&P 500 Index has clocked four consecutive weeks of declines and it’s on track for the worst month in a year.

To get a sense of where the pain may end, many equity traders look to a type of technical analysis credited with identifying the bottoms of big market declines, including two major routs since 2020. The bad news for bulls: It signals a long way down before the index finds major support.