Most presidents have clashed with business interests and industries, sometimes in ways that generated headlines. But Mr. Trump is unique in singling out individual companies for ridicule with regularity. And rarely have presidents done so because of a personal pique or grudge, as happens with Mr. Trump.
“This is an unprecedented situation for companies. The president’s tweets can cause significant reputational harm,” said Dean C. Garfield, the president of the Information Technology Industry Council, which represents big technology companies like Amazon, Dell, Facebook, Google and IBM. “We are now at a place where about 90 percent of the companies we represent now have a presidential Twitter strategy in place.”
“It’s no laughing matter,” he said.
For many companies, that strategy comes down to waiting out the storm. In recent days, Amazon has all but ignored the president’s taunts, which he issued in a flurry of tweets.
“There’s no real advantage going toe-to-toe with him,” said Joe Lockhart, a press secretary for President Bill Clinton who was a spokesman for the National Football League, another favorite target of Mr. Trump. “And his attention span is so short, he will move on. He’ll find another target.”
Associates say the president is often riled up by Amazon’s connection to The Washington Post, whose owner, Jeff Bezos, founded the retail giant. People close to the president have said his attacks on one of the country’s largest businesses have usually been prompted by articles in The Post that Mr. Trump perceives as negative.
Likewise, the president’s interest in the AT&T merger with Time Warner largely stems from his repeated clashes with CNN, a subsidiary of Time Warner, which he regards as biased against him.
Mr. Trump’s lashing out at the N.F.L. — he has repeatedly criticized football players for kneeling at games and once said he hoped a player “sues the hell out of the @nfl for incompetence & defamation” — comes in part from his decades-long legal fight with the N.F.L. after he bought a team in the competing United States Football League.
As a private citizen, Mr. Trump has attacked companies, including calling several times for boycotts. The remarks served to raise his profile and fed the image of a no-holds-barred businessman who was unafraid to rebuke his rivals or his critics. But in those days, such comments had little ability to move stock prices or affect sales.
As a candidate and as the president, Mr. Trump also uses his verbal assaults on companies to bolster his populist message that he is on the side of workers, not big business. (Still, Mr. Trump secured a large tax cut last year for corporate America.)
Mr. Trump’s most ardent supporters say they appreciate his willingness to criticize the corporate establishment.
“He continues to go directly after the companies and not care about political correctness,” said Terry Bowman, a former Trump campaign organizer who works at a Ford Motor parts factory in Ypsilanti, Mich. “He says things that a polished politician would never say. He says things that come directly from the American worker.”
President Barack Obama once singled out Staples, the office supply company, for failing to provide more health care for its employees. “Shame on them,” he said. Earlier in his presidency, Mr. Obama broadly criticized Wall Street bankers whose firms took federal bailout money only to turn around and award bonuses to their executives.
“That is the height of irresponsibility,” Mr. Obama said in 2009 without identifying specific companies. “It is shameful.”
Mr. Clinton’s Justice Department aggressively pushed to break up Microsoft on the grounds that it was abusing its monopoly position in personal computing to dominate the internet.
President John F. Kennedy avoided naming individuals during a fight with the steel industry in 1962. He criticized “a tiny handful of steel executives whose pursuit of private power and profit exceeds their sense of public responsibility.”
President Franklin D. Roosevelt frequently assailed the “malefactors of great wealth” without identifying them.
Mr. Trump has had no such reticence.
In his most recent attacks on Amazon, he has accused the company of using the United States Postal Service as “its Delivery Boy” and claimed that the federal agency was being ripped off by the online retailer. On Tuesday, he insisted that he was right.
“A report just came out. They said $1.47, I believe, or about that for every time they deliver a package, the United States government — meaning the post office — loses $1.47,” the president said.
He added, ominously: “So Amazon is going to have to pay much more money to the post office. There’s no doubt about that.”
Mr. Trump’s numbers were inaccurate — the Postal Service makes money from Amazon — but business executives say such statements have a chilling effect.
When Merck’s chief executive, Kenneth C. Frazier, quit a presidential business council last year in protest of some of the White House’s policy positions, other members were initially reluctant to come to his defense for fear of a verbal attack by Mr. Trump. The council eventually disbanded but only after much internal negotiation among members to quit in force.
The multiday decline of Amazon’s stock price after Mr. Trump’s repeated jabs at the company has exacerbated such fears, said Jeffrey A. Sonnenfeld, a professor at the Yale School of Management and president of the Chief Executive Leadership Institute.
“Other business leaders don’t want to catch the contagion,” he said.
But he added that refusing to engage could also be risky. He said that Mr. Bezos’s silence had hurt the company, leaving it exposed to Mr. Trump’s accusations that it received subsidies from the Postal Service and was not paying its fair share of taxes.
“The right answer for C.E.O.s is not to engage in a mud fight but to come with facts,” Mr. Sonnenfeld said. “U.P.S. and FedEx have their facts, but we haven’t heard from Amazon.”