Stocks finish their worst month of 2019

Stocks fell sharply in the final day of May trading, following President Trump's surprise decision to slap tariffs on Mexican imports.

The bottom line: The S&P 500 lost 1.32% on Friday, bringing the total May loss to 6.58%. That's the index's worst monthly performance of 2019, after having hit an all-time high back in April, and puts it just 1.73% higher than at this point in 2018.