Heidi N. Moore is a business editor and consultant. She has been an editor, columnist and reporter for publications including the Guardian U.S. and the Wall Street Journal.

One of the perks of being president is the ability to pick fights with anyone you want in the name of national interest. That’s why Teddy Roosevelt dubbed the presidency the “bully pulpit” for its ability to intimidate companies like JP Morgan into complying with his policies, and why President John F. Kennedy could confidently declare after picking a fight over the price of metal with U.S. Steel, “My father always told me that all businessmen were sons of b——.” Even President Barack Obama, one of the milder-mannered leaders in the White House, told Staples and other companies resisting his health-reform ideas that they should be ashamed of themselves. Historically, presidents have jabbed at private businesses frequently to make them get with the program on issues of major policy.

President Trump is using this tool rather differently.

As he picks fights with over a dozen large U.S. companies through nastygrams on Twitter — the Wall Street Journal even created a “Trump Target Index” to track the stock prices of the companies he insults — Trump’s sights are set on something other than the national interest. This president attacks private businesses to settle personal scores: To reward friends or punish enemies, to lash back at companies who criticize him, to be a kingmaker who chooses who wins and who loses the great game of capitalism. Walmart is his friend, so he attacks Amazon. Nordstrom drops his daughter’s clothing line, so he goes after them. CNN’s journalism offended Trump, so he attacks its parent, Time Warner; the same goes for NBC, whose license he (emptily) threatened to pull in October. Trump has aimed critical tweets at many of America’s other biggest companies: Apple, Carrier, Toyota, General Motors, AT&T and Ford. It has escaped no one’s notice that his war with Amazon and chief executive Jeffrey P. Bezos most likely has links to Trump’s fury at The Washington Post, which Bezos owns but whose editorial decisions are independent. Trump’s own business conflicts are so embedded in his presidency that he can’t seem to imagine that other executives don’t have them as well — perhaps one reason the emoluments case against him is still going strong.

There’s every reason to worry when a president is trying to destabilize American companies, even temporarily. But the great comfort is Trump’s own lack of focus and the haphazard way his administration works. While he may cause some damage — and he has — it’s doubtful his attacks will leave many long-term scars.

There’s no question that Trump’s Twitter tantrums have some effect: His tweets about Amazon brought down the company’s stock price by over 5 percent. But it’s a clumsy, and often far too blunt, way to go after his enemies. In the process of complaining about Amazon and the U.S. Postal Service, he also took down the entire sector of tech stocks and, according to some pundits, might have helped cause a 500-point drop in the Dow Jones industrial average on Monday. When Trump announced a plan for tariffs on steel and aluminum in early March, the Dow tanked by 420 points in a day, and Trump’s top economic adviser, Gary Cohn, quit. While Trump’s corporate targets suffer a temporary stock dip, they usually rebound fast, Reuters found. That Wall Street Journal’s “Trump Target Index” that judged how his tweets affected major companies discovered that stocks that Trump attacked actually ended up rising so much afterward that they jumped in value more than the overall stock market did. Not exactly chilling results.

Unlike Roosevelt, Kennedy or Obama, Trump’s presidency comes with a credibility problem that undermines most of his statements. He changes his mind so often that it’s hard to trust any of his pronouncements will become policy, as seen in his multiple about-face statements on immigration. His campaign associates are being indicted in batches — and sentenced to jail time — by Robert S. Mueller III, the special counsel investigating Russian meddling in the 2016 election. And Trump’s approval ratings are low, with 54 percent of the country disapproving of his performance.

Trump has so much trouble making friends, in fact, that there may be some benefit in being on his enemies list. “If you’re Amazon, and you have your own political clout, maybe it helps me to be on the other side of him. His credibility is so limited that would you even want his support?” said Paul Argenti, a professor of corporate communication at Dartmouth’s Tuck School of Business. “Does it really matter to Amazon what President Trump thinks about them? Is it Amazon who has more power or is it Trump? It’s not completely clear.”

That doesn’t mean Trump’s Twitter vendettas should be completely dismissed. He relishes his ability to declare winners and losers, and he has shown a stubbornness in his revenge against major U.S. companies. Several corporations have learned that, once Trump’s ire against them is public, even the most fulsome flattery won’t reverse his anger or his vengeance, as Time Warner found out when it tried to support Trump’s tax bill only to face antitrust trouble from his administration anyway. The president — any president — can cause real damage through regulatory means if not through the stock market.

And Trump’s wrath is most intense against major media companies — though, of course, not Fox. In October, for instance, he tweeted about pulling the TV license for Comcast-owned NBC; by December, even though TV stations are licensed individually, not by network, Comcast was currying presidential favor with an announcement that the company would pay out $1,000 bonuses to staffers to celebrate Trump’s tax bill. Similarly, Time Warner and Walmart made big shows of paying bonuses to support Trump’s tax move.

Fat lot of good it did Time Warner, however. Despite the company’s support for the tax bill, Trump has attacked CNN and its chief “Little Jeff Zuker (sic)” as an enemy of his administration, and the Justice Department is suing to stop an $85 billion proposed merger between Time Warner and AT&T. AT&T’s lawyers seek to prove Trump, who tweeted aggressively against the combination of the two companies, meddled in the merger review. The case is pending in federal court.

Even Trump-friendly companies can’t count on the famously disloyal president to help their cause. Take right-wing Sinclair, which Trump has praised in a tweet as an alternative to the major networks. Sinclair’s effort to buy Tribune Media for $3.9 billion is still facing a longer-than-expected review from Trump’s Justice Department.

This is why Trump’s variation on keeping companies in line inevitably fails: Previous presidents attacked companies to get them to play by the rules of the game. Trump’s attacks are based only on his personal moods and vendettas, which can change at any minute, so it’s impossible for his targets to understand the rules and adjust their actions accordingly.

And Trump is missing the key lesson from previous presidential criticisms of corporations: If you pick the winners, you better pick the right ones, or you look foolish. Roosevelt, Kennedy and Obama took on corporations intentionally and with a stated policy purpose. Trump’s attacks are unfocused and vengeful, increasing the risk that he will end up losing more standing. The weakest president in American history is taking on the most powerful of its companies. In the end, it’s a safe bet that the businesses will outlast Trump’s troubled presidency.

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