Market corrections in Europe and Asia have traders worrying the U.S. could be next.
That has some investment managers warning traders to tread with caution.
"It's definitely flashing yellow all across the world," said Boris Schlossberg, managing director at BK Asset Management. "At the very minimum, investors should take some protection, maybe in terms of buying puts."
The world's economy has been on the minds of many traders. Last week, the Organization for Economic Cooperation and Development cut its 2015 global growth estimates to 3.1 percent from its earlier projection of around 3.7 percent. "The first quarter of 2015 saw the weakest global growth since the [financial] crisis," said OECD chief economist Catherine Mann.
A long-standing debate among U.S. investors is the extent to which slowing global growth will be a concern for American stocks.