But real estate projects like the Kushner Companies’ deals have become a magnet for opaque foreign money — often from parts of the world that present thorny policy questions, such as China, where Mr. Kushner’s company has actively sought investors, as well as the Middle East and Russia. As part of his exceptionally broad portfolio in the White House, Mr. Kushner has been a crucial figure in arranging the visit of the Chinese leader, Xi Jinping, on Thursday in Florida.
The mystery behind many real estate investments involving foreigners prompted the Treasury Department last year to push for additional disclosures as a way to combat money laundering.
While Mr. Kushner may face a potential ethical minefield, the disclosure form makes it difficult to determine exactly where those mines might be situated. The form, which runs 54 pages and lists hundreds of entities, reveals few details about the underlying investments that make up the Kushner empire, such as the addresses of buildings, sources of financing and names of partners.
John Pudner, a conservative who has helped elect Tea Party candidates to Congress and now runs a nonprofit group called Take Back Our Republic, said that Mr. Kushner and Ms. Trump, if they wanted to serve in the White House, would have been better off if they had taken the difficult step of liquidating their holdings.
“A win-win for the president’s family and everyone else is if there were no question anytime a decision is made that it’s being done for the good of the country,” he said.
The actions by Mr. Kushner stand in contrast to the moves by some other top aides to Mr. Trump, such as Secretary of State Rex W. Tillerson, the former chief executive of Exxon Mobil, who before he was sworn in agreed to liquidate all of his stock holdings and his ownership stake in Exxon, putting his assets mostly into Treasury bonds and other permitted investments, such as diversified mutual funds, which make formal financial conflicts unlikely.
Mr. Kushner, by contrast, continues to hold multimillion-dollar lines of credit from institutions such as Citigroup and Deutsche Bank, while companies he is still a beneficiary of have billions of dollars in additional loans from heavily regulated institutions.
Richard W. Painter, who served as a White House ethics lawyer in the Bush administration, said that Mr. Kushner’s financial holdings would complicate any interactions he might have with such banks. “The one thing Jared really ought to stay completely away from is anything having to do with Dodd-Frank,” Mr. Painter said, referring to the 2010 law that increased capital reserve requirements and instituted many other regulatory changes that affected the nation’s banks.
Mr. Trump has already said he hopes to roll back the law, with the help of Congress and his top aides.
Several of the companies that are in business with Kushner Companies have faced scrutiny by federal law enforcement. Deutsche Bank, for example, reached a $7.2 billion settlement last year with the Justice Department over its sale of toxic mortgage securities.
Mr. Kushner, who frequently speaks with world leaders and is tasked with overseeing Middle East peace negotiations, also has an unsecured line of credit worth as much as $5 million from Israel Discount Bank. Kushner Companies has also taken out at least four loans from Bank Hapoalim, Israel’s largest bank, though they are not disclosed in the filing. That firm is the subject of a Justice Department investigation into whether it helped wealthy Americans evade taxes with undeclared accounts.
Another potential conflict rests in Ms. Trump’s continued stake in the Trump International Hotel in Washington, a project that has drawn protests from ethics experts who worry that people representing special interests could stay there or host events there to gain influence with the White House, which is just a few blocks away.
Ms. Trump has rolled her fashion brand into the Ivanka M. Trump Business Trust, which is overseen by her brother-in-law, Josh Kushner, and sister-in-law, Nicole Meyer. The documents released on Friday valued the trust at more than $50 million.
Discussions about changes in federal tax law — a major agenda item for Mr. Trump that could affect issues such as depreciation on Mr. Kushner’s buildings and clothing imported for Ms. Trump’s brand — could also pose problems, or force them to recuse themselves from participating.
“They are going to have to walk a fine line between matters they are involved with financially and the policies they are helping create and legislation they may be advocating,” said Scott H. Amey, general counsel at the Project on Government Oversight, a nonprofit group.
The federal ethics regulations formally prohibit federal employees from being involved in any “particular matter that will have a direct effect on a financial interest, if there is a close causal link between any decision or action to be taken in the matter and any expected effect of the matter on the financial interest.”
But Mr. Painter said that most administrations had interpreted the law more broadly, so that officials who own stakes in individual industries do not participate in even broad policy decisions affecting that sector, unless they seek a formal ethics waiver, as certain officials did during the first George Bush administration, given that they owned energy industry stocks and were participating in the decision to enter the war against Iraq over its invasion of Kuwait.
Federal employees, under ethics rules that Mr. Trump imposed, are also prohibited, for at least two years after they arrive in the government, from working on particular matters that involve former employers or clients, even if these actions do not directly financially benefit the federal employee.
The disclosures by Mr. Kushner and other White House officials released on Friday demonstrate just how complicated it is going to be to police these rules, given the vast and extremely complex financial assets not only within the Trump family but also among dozens of aides they have selected.
The National Economic Council director, Gary Cohn, as well as the top White House aides Christopher P. Liddell and Reed Cordish, collectively reported assets with a maximum value of more than $1 billion. Stephen K. Bannon, Mr. Trump’s chief strategist, reported assets worth as much as $53.9 million. Even Mr. Bannon’s aide Julia Hahn, who is 25, reported investments worth between $1 million and $2.1 million, according to a tally by The New York Times, while Kellyanne Conway, counselor to the president, had assets worth between $11 million and $44 million.
Some of those financial holdings are already creating questions.
Mr. Liddell, an assistant to the president and the director of strategic initiatives, has participated in White House meetings since January that involved several companies in which he continued at least through February to own stock in, including International Paper and General Motors.
Mr. Bannon disclosed more than $500,000 in income from entities linked to the hedge fund manager Robert Mercer and his daughter, Rebekah Mercer, major Republican donors who were crucial figures in Mr. Bannon’s appointment as the Trump campaign’s chief executive last year.
Mr. Bannon is selling off some of these assets, his financial disclosure report says, including shares in Cambridge Analytica, the political consulting firm, and Breitbart News, the right-wing website. But Mr. Bannon, even after joining the White House, has continued to interact with certain reporters at Breitbart, at times to express frustration with the site’s coverage of the White House or to discuss coverage, editors there have said.
Even Treasury Secretary Steven Mnuchin, a former hedge fund manager, wrote a letter on Friday to the Office of Government Ethics saying he should not have made a supportive remark about a film, “The Lego Batman Movie,” that one of his companies helped produce. The comment was viewed by some as a commercial endorsement of the film.
“The White House staff’s massive businesses are creating so many possible conflicts of interest it seems almost impossible for them to avoid running into trouble as they mix their former business interests with their new professional duties,” Mr. Bookbinder said.