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.