Stock market downturns present risks to leveraged investors, according to one chief economist.

A futures-options trader works on the floor at the New York Stock Exchange in New York City. Brendan McDermid/Reuters
U.S. investors keep borrowing money to buy the dip or take part in new stock market highs.
Margin debt—loans taken out by investors from brokerage firms to buy stocks—climbed to a record high of $1.279 trillion in January, according to data from the Financial Industry Regulatory Authority (FINRA).


