The Dow Is Down. The Dow Is Up. Either Way, It's Not Because of the President.

Markets respond to politics, but presidents shouldn't claim control.

President Donald Trump has been bragging pretty hard about how much the stock market is up under his presidency. Today is a good demonstration of why that's a bad idea. Because, while it's not quite true that what goes up must come down, markets don't tend to have four-year or eight-year uninterrupted booms. The Dow was down 1,500 points today. It popped back up a bit, but is still down about 1,000 points at the close of the market. And this probably isn't the end of the volatility.

The president has a bad habit of taking credit for things outside of his control—low airline fatalities and the incidence of Christmas wishes are among the things he's claimed just recently—and the stock market falls into that category.

During last week's State of the Union, the president grabbed big applause for this line: "The stock market has smashed one record after another, gaining $8 trillion in value."

But with the market down, suddenly it's: "We're always concerned when the market loses any value, but we're also confident in the economy's fundamentals," from unnamed spokesmen.

If the afternoon's rally continues, expect the POTUS to return to crowing. He shouldn't.

It's always tempting to see shifts in the market as evidence that our own pre-existing beliefs are being corroborated. But the markets do seem to be reacting to two big pieces of news out of Washington today: new debt figures, fueled by the tax cuts, which are going into effect now without any offsetting cuts in spending. That decision will push the deficit even higher and has pushed up that date at which Congress must once again grapple with the debt ceiling. Add to that concerns that the Federal Reserve will adjust interest rates in reaction to signs that the economy is heating up, including new wage data out Friday, and investors are freaking out a bit.

Presidents don't control markets. This isn't to say that markets don't respond to politics; of course they do. But when you try to take (misplaced) credit for the ups, you have to grapple with the downs, too. And that's something Trump's not willing or able to do.

P.S. Black unemployment, which was previously at a low that had the president boasting all over the place, has spiked back up as well. Same deal: The president neither gets all the credit nor all the blame.