Pointing to data showing run-ups in foreign purchases of U.S. stocks before the 1987 crash, the dot-com bubble in 2000, and the 2008 financial crisis, Ed Yardeni wrote in his eponymous research newsletter, "Their buying has a record of being a contrary indicator. They tend to be big buyers right before bear markets."

While President Donald Trump's tariffs are front and center in many investors' minds, a handful of stocks have sold off despite being relatively unaffected. This is a guilty-by-association reaction and a great opportunity for investors to scoop up shares.

Stocks are rallying worldwide Monday after President Donald Trump relaxed some of his tariffs, for now at least, and as stress from within the U.S. bond market seems to be easing. The S&P 500 was up 1.