Although he has tweeted in the past about companies such as Boeing, Carrier and U.S. automakers, ethics experts said the fact that this one was about his daughter's business raises conflict-of-interest concerns and even carries an implicit threat.
In the message, Trump said, "My daughter Ivanka has been treated so unfairly by @Nordstrom. She is a great person — always pushing me to do the right thing! Terrible!"
Posted first on his personal account, it was retweeted more than 6,000 times in less than an hour. It was also retweeted by the official presidential Twitter account.
Trump's presidency has raised unprecedented concerns about ethical conflicts. His plan to separate himself from his sprawling real estate business has been criticized by ethics experts, who say it doesn't do enough to make sure that Trump won't make decisions to personally benefit himself, his family or his company.
Nordstrom reiterated Wednesday that its decision was based on the brand's poor performance. The company's shares dropped after the tweet, like others Trump has mentioned in the past, but they later recovered, closing up 4.1%.
Kathleen Clark, a government ethics expert, said the Nordstrom tweet is problematic because other retailers may think twice now about dropping the Ivanka Trump brand for fear of getting criticized publicly by the president. She said it was especially disturbing that Trump retweeted his message on the official White House account.
"The implicit threat was that he will use whatever authority he has to retaliate against Nordstrom, or anyone who crosses his interest," said Clark, a law professor at Washington University in St. Louis.
Clark defended the president's right to use his personal Twitter account to express his views, however: "A government employee, even a president, is allowed to tweet in his personal capacity."
A social media campaign called Grab Your Wallet has urged a boycott of stores that stock Ivanka Trump or Donald Trump products, though the companies that have stopped ordering or cut back on the Ivanka Trump brand have not mentioned it.
Nordstrom said last week that its decision was based on the Ivanka Trump brand's performance, and that each year it replenishes about 10% of its supply with new products. There are more than 2,000 products on its website alone. "Reviewing their merit and making edits is part of the regular rhythm of our business," it said.
Retailer Belk Inc. said in an email Wednesday that it will no longer be carrying the Ivanka Trump brand on its website but will still offer the merchandise at its stores. The New York Times reported that TJX Cos., which operates T.J. Maxx, told employees not to display Ivanka Trump goods separately and to discard the brand's signs, according to a memo obtained by the paper. TJX spokeswoman Doreen Thompson said in an email that "at this time, we continue to offer the line of merchandise."
Rosemary K. Young, senior director of marketing at Ivanka Trump, said last week that the brand is expanding and saw "significant" revenue growth last year compared to the previous year. Ivanka Trump herself has said she would take a leave of absence from her clothing and accessories business as well as the Trump organization.
White House spokesman
"For someone to take out their concern with his policies on a family member of his is not acceptable," Spicer said.
Trump's tweet was posted at 10:51 a.m. EST, a little more than 20 minutes after the scheduled start of the president's daily intelligence briefing in the Oval Office. Spicer waved off reporters' questions about the timing, saying the president was not otherwise occupied when he wrote the tweet.
It's not the first time Trump's tweets have at least temporarily affected a stock. But companies are clearly wrestling with a new dynamic.
"What we are seeing is that we are living in a world with a different kind of chief executive in the White House," said Matthew Shay, president and CEO of the National Retail Federation trade group. "He has a strong opinion on issues. We are learning to work in the environment."
The president’s tweet came the same week that attorneys for his wife,
In court documents filed Monday, her lawyers said the "multiyear term" during which she "is one of the most photographed women in the world" could mean millions of dollars for her personal brand.
Although the documents didn't specifically mention Melania Trump's term as first lady, the unusual statement about her expected income drew swift condemnation from ethics watchdogs as an attempt to inappropriately profit from her high-profile position, which is typically centered on public service.
Charles Harder, Melania Trump's attorney, said "the first lady has no intention of using her position for profit and will not do so. It is not a possibility. Any statements to the contrary are being misinterpreted."
Harder did not respond to a follow-up question about what the lawsuit means by "once-in-a-lifetime opportunity."
The Trumps' marketing has drawn scrutiny before.
Ivanka Trump's business also came under fire last fall, days after the presidential election, when she appeared on CBS' "60 Minutes" wearing a nearly $11,000 gold bracelet from her jewelry line and someone from the company sent out a marketing email with photos from the interview, seeking publicity for the line.
On inauguration day, the official White House biography for the first lady originally referenced her jewelry collection, which it noted was sold on the home-shopping channel QVC. By the next day, that bio had been edited and simplified to say she had "launched her own jewelry collection."
President Trump continues to financially benefit from his global business empire, breaking from past practice. Previous presidents and their families have divested from business interests and placed their holdings in blind trusts, although there is no legal requirement to do so.
Trump handed daily management of the Trump Organization's real estate, property management and licensing operations to his adult sons and a longtime employee.
2:25 p.m.: This article was updated with comments from ethics expert Kathleen Clark and with Nordstrom shares' movement.
1:15 p.m.: This article was updated with comments from the White House, Belk and TJX, with Nordstrom shares' movement and with additional details.