Donald Trump and his Twitter account continue to dominate headlines on this Monday, which forecasts one heck of a week for ongoing cabinet selections amid the Russia and China situations. Trump is not only the future leader of the free world but — underneath it all — a celebrity, which grants him great influence on Twitter. Today, Trump proved that a single tweet can severely impact a company’s bottom line.

That’s what happened with Lockheed Martin, which recently finalized a $6.1 billion deal with the Pentagon to produce the stealthy F-35 fighter jets. The company’s stock took a major hit when Trump slammed the F-35 program’s cost and hinted that, come Inauguration Day, “billions of dollars” may no longer be spent on a certain defense contractor.

The F-35 program and cost is out of control. Billions of dollars can and will be saved on military (and other) purchases after January 20th. — Donald J. Trump (@realDonaldTrump) December 12, 2016

Let’s take a look at that plummeting stock, shall we?

Lockheed Martin shares drop sharply after Trump tweets about "out of control" F-35 program costs. https://t.co/DlQWTKRBwH pic.twitter.com/8TYnVaXpQa — CNBC Now (@CNBCnow) December 12, 2016

CNBC places the damage at $4 billion (a 3% downswing) all because of one tweet. This presents terrifying prospects, for Trump often tweets randomly, angrily, in the middle of the night, and without thinking. Was this Lockheed Martin tweet planned in advance? It’s possible, or Trump could simply be “keeping it real” like he enjoys doing.

This presents obvious difficulties. There’s little doubt that Trump’s a loose cannon and freely speaks his mind, which is why so many voters — who were sick of the stuffy GOP establishment — chose him as their leader. However, those same blue-collar workers who clamored for “Make America Great Again” ball caps could lose their livelihoods as a result of these tweets. And then Michael Moore will make the rounds for another “rude awakening” discussion.