The White House expressed confidence in the U.S. economy amid a massive sell-off on Wall Street.

“Look, markets do fluctuate in the short term. I think we know that,” White House spokesman Raj Shah told reporters on Monday.

ADVERTISEMENT Despite that, Shah said, the “fundamentals of this economy are very strong and headed in the right direction for the middle class in particular,” citing wage growth and employee bonuses handed out following passage of the GOP tax bill.

The Dow Jones industrial average was down more than 400 points on Monday . That followed a turbulent Friday , when the Dow lost 666 points in its worst day since the summer of 2016.

Trump has repeatedly touted gains on Wall Street since his election as evidence his economic policies are working.

"The Fake News Media barely mentions the fact that the Stock Market just hit another New Record and that business in the U.S. is booming...but the people know!" Trump tweeted last month. "Can you imagine if “O” was president and had these numbers - would be biggest story on earth! Dow now over 25,000."

Before Trump, U.S. presidents have largely refrained from commenting on the stock market to avoid being tied to its performance.

Trump has not yet been forced to deal with significant losses in the markets. The Dow is up more than 30 percent since he was elected president in November 2016.