As the controversial Republican prepares to enter the White House following his shock US election win, questions are now being asked about how the he will juggle his dual roles as head of a multibillion-dollar international business empire and president of the United States.
With sprawling investments in hotels, office towers, apartment buildings, residential real estate, resorts, golf courses and entertainment, observers are describing the scale of Trump's potential conflicts of interest as "unprecedented".
While congressmen, senators and other high level public servants are required to disclose financial interests and recuse themselves from government business that could generate a conflict, no such restriction exists for presidents and vice-presidents.
As author David Sirota explains, legal exemptions introduced in 1989 mean all Trump is required to do is file a standard financial disclosure from the Office of Government Ethics to the Federal Election Commission. Trump's form, which he filed in 2015, was the longest in the history of the FEC at 104 pages.
"The scope of Trump's potential conflicts is vast," Sirota writes in the International Business Times. "He owns stock in defence contractors; on the campaign trail, he vowed to increase the size of the US Navy. Trump Palace Condominiums, one of his subsidiary companies, leases to the federal government, meaning President Trump is poised to become his own company's landlord.
"Trump also owes millions of dollars to Deutsche Bank - which is currently negotiating a fraud settlement with the Department of Justice, an agency which President Trump will oversee."
Sirota also raises another interesting question: will Trump have to take his name off his buildings? "Trump-branded properties could provide a way for regulators to pierce the presidential immunity from conflicts laws," he writes.
"The 1989 Ethics Reform Act ... prohibits any senior 'non-career' government 'officer' from having their name 'used' by any firm involved in fiduciary arrangements."
The catch is a rule exempting presidents and vice-presidents from the category of "officer", but a simple rule tweak could cause all sorts of problems.
It's not just domestic issues, either. Trump's real estate empire is primarily located in the United States, but also extends to countries such as South Korea and Turkey. Managing political relations with such US allies while president risks creating a curious mix of competing goals.
US media have reported the Trump Organisation has financial ties with people close to Russian President Vladimir Putin, who the real estate mogul praised leadership during his campaign.
"For the record, I have ZERO investments in Russia," Trump tweeted in July. The potential for conflicts of interest from Trump's business activities are not limited to countries like Russia.
"The number of problems is actually sort of mind-boggling," Trevor Potter, former head of the Federal Election Commission, told NPR.
The Trump Organisation is not publicly traded, so many of its activities are closed to scrutiny. The problem takes on another dimension with Trump, whose name is inextricably tied to his business empire.
"It's unprecedented in the history of the US in part because we don't know the scope or the nature of his many financial ties in particular," Kathleen Clark, a law professor at Washington University in St. Louis, told AFP.
She said one ethical point of particular concern is that Trump financed his company's expansion through debt. "We don't know to whom he owes money. In some ways owing money is a much more significant financial contact than an investment," she said.
Potter also pointed out that Trump's new hotel on Pennsylvania Avenue in Washington, just down the road from the White House, had been built in the old federal post office building, which required him to negotiate a lease with the US government's General Services Administration.
"You're going to have a situation where the president appoints the head of GSA, and then the president's most visible asset in Washington is potentially subject to negotiation with that person over the terms of the lease and any changes in the lease," Potter told NPR.
Trump had pledged during the campaign to entrust his business to a blind trust which would wall him off from any say in the company's activities, and said he would hand over control of his business empire to his children if he won.
"If I become president, I couldn't care less about my company," he said during a debate in January. "It's peanuts. I want to make America rich again and to make America great again. I have Ivanka and Eric. Run the company, kids. Have a good time. I'm gonna do it for America!"
Trump's three children, Donald Jr, Eric and Ivanka, are already executive vice presidents of the Trump Organisation. "We're not going to discuss those things," Donald Jr said in September, referring to the company's business dealings. "Trust me. As you know, it's a very fulltime job. He doesn't need to worry about the business."
But Robert Weissman, president of the liberal advocacy group Public Citizen, said the idea that there would be independence was "laughable". "There's zero reason to expect they wouldn't talk about those issues, given everything we know about how they relate and how those businesses are run," he told NPR.