With his Twitter blast at Nordstrom, President Donald Trump sparked fresh concerns that he and his family are using the Oval Office for personal gain.

Trump accused the department store chain on Wednesday of treating his daughter Ivanka "unfairly," prompting its stock to drop briefly before it recovered. The president's tweet came days after Nordstrom said it would not sell his daughter's brand in the upcoming season due to sagging performance.

Trump's tweet, later distributed by the official "@POTUS" account, pulled him back into a debate over whether he did enough to distance himself from his family's businesses when he took office. The president chose not to divest from the Trump Organization, handing control to his two eldest sons and a company executive.

While the Trump Organization said Ivanka Trump stepped down from her roles there, she licenses her name to merchandise manufacturers, who then sell products at stores like Nordstrom and Macy's, according to The New York Times. It's not clear if she still receives royalties from her clothing licensing.

Trump's criticism of a company that distanced itself from his daughter's brand shows "un-presidential behavior and potentially much worse," said Richard Painter, a former top White House ethics lawyer under President George W. Bush.