Since President Trump was elected a second time, he and his allies have raised nearly $2 billion for his favored political causes and passion projects. That total, which was confirmed by four people involved in the fund-raising, likely eclipses the amount raised to support his 2024 campaign.

The astounding haul hints at a level of transactionalism for which it is difficult to find obvious comparisons in modern American history. The identities of the donors behind much of the cash are not legally required to be, and have not been, publicly disclosed. In some cases, Mr. Trump’s team has offered donors anonymity.

To shed light on what has been a largely opaque fund-raising apparatus, The New York Times conducted a comprehensive investigation. It relied on previously unreported documents and public campaign finance filings, as well as interviews with dozens of people who are familiar with the solicitations or are involved in the fund-raising. It traced a large portion of the funds raised — more than half a billion dollars’ worth — back to 346 donors who each gave at least $250,000. It also found that more than half of them have benefited, or are involved in an industry that has benefited, from the actions or statements of Mr. Trump, the White House or federal agencies.

It is not possible to prove that any of the donations directly led to favorable treatment from the Trump administration. And the contributions do not personally enrich Mr. Trump, unlike some of his family’s cryptocurrency ventures.

But many of the deep-pocketed individuals and corporations who have given large sums have a lot riding on the administration’s actions, raising questions about conflicts of interest.

Presidents of both parties have raised funds for their inaugurations, and many major companies have long histories of donating to them. But second-term presidents usually begin winding down their own fund-raising after their inaugurations, focusing instead on boosting their parties’ committees and candidates.

Mr. Trump, on the other hand, was emboldened by the record-breaking sum of nearly $240 million raised by his inaugural committee. He immediately tasked his fund-raising team, led by his campaign’s finance director, Meredith O’Rourke, to raise money for an array of groups and causes supported by the president, according to three people involved in the fund-raising. They requested anonymity to discuss nonpublic information, as did five others who discussed other elements of the fund-raising.

It is a buffet of options that allows donors to pay tribute to Mr. Trump and sometimes receive access to him to pitch their own interests. While the groups raising funds are independent from one another, and some are nonpartisan, they are presented to donors as part of a fund-raising apparatus to which Mr. Trump or his allies would like them to give, according to four people familiar with the fund-raising. They said Mr. Trump closely tracks which companies have given, and how much, debriefing regularly with Ms. O’Rourke.

Lobbyists with connections in Mr. Trump’s orbit recommend that their clients donate to these groups to try to win him over, said five people familiar with the fund-raising.

“In this town, money talks, and that is going to give you an opportunity to at least have a seat at the table,” said Harrison Fields, a former Trump White House official who left in August and became a lobbyist. His firm, CGCN Group, has represented companies that have donated to projects Mr. Trump supports, including the new White House ballroom, America250 and MAGA Inc.

“These people are not getting coerced. They are making business decisions,” said Mr. Fields.

At least 51 of the donors have given to more than one of the groups in this analysis since the election.

While MAGA Inc., the inaugural committee and the Republican National Committee (another entity for which Trump-allied fund-raisers are soliciting money) are required to disclose their donors to the Federal Election Commission, there is no such requirement for contributions to other groups for which the president’s allies are raising funds.

Those groups include the Trust for the National Mall, America250, the White House Historical Association, a political nonprofit group called Securing American Greatness and the John F. Kennedy Center for the Performing Arts, which Mr. Trump’s allies have remade in his own image, including adding his own name to the title and the building’s facade.

The Times’s investigation identified a number of donations, or potential benefits to donors, that had not been publicly known.

One $2.5 million contribution to MAGA Inc. was given by a South Florida woman whose father months later received an unusually lenient deal from top Justice Department officials to settle charges that he bribed Puerto Rico’s then-governor in 2020.

Another $2.5 million pledged donation — this one to Mr. Trump’s White House ballroom project — came from Parsons Corporation, an engineering firm that has won government contracts for years, including under Mr. Trump, and is jockeying for some of the more than $1 trillion in contracts that could be awarded to build a missile defense system proposed by the president called the “Golden Dome.” Also giving $2.5 million to the ballroom project was the chief executive of Roblox, a popular online video game company that has applauded a Trump executive order and other initiatives involving children’s use of artificial intelligence.

A couple who donated $1 million to Mr. Trump’s inaugural committee and $500,000 to MAGA Inc., as well as an undisclosed amount to the ballroom fund, saw Mr. Trump nominate their son to be U.S. ambassador to Finland.

And a company that was accused last year by the Justice Department of colluding over ticket prices donated $250,000 to Mr. Trump’s inauguration. The president pardoned the company’s co-founder in a separate case this month.

In other cases, The Times was able to quantify large donations for which the amounts were previously unknown. Those included gifts from the technology firm Palantir, which donated $10 million to the ballroom project and $5 million to America250. Additionally, the Palantir co-founder Alex Karp donated $1 million each to the inauguration and to MAGA Inc. In Mr. Trump’s second term, Palantir has secured federal contracts worth hundreds of millions of dollars, including to develop software to help Immigration and Customs Enforcement deport people. But a Palantir official said in a previously unpublished response to an inquiry from Senator Richard Blumenthal, Democrat of Connecticut, that the company did not seek and was not offered any special consideration for its donation to the ballroom project.

While a foundation funded by Miriam Adelson, a casino magnate, mostly supports Jewish and Israeli causes, it pledged to donate $25 million to the ballroom project, according to two people familiar with the donation. In a speech at a White House Hanukkah party last week, Mr. Trump praised Dr. Adelson, a physician by training, for donating tens of millions of dollars to help his campaigns and using her access to lobby for greater U.S. backing for Israel. Calling her to the lectern, Mr. Trump said, “When somebody can give you $250 million, I think that we should give her the opportunity to say hello.” The two embraced and bantered about how Dr. Adelson would be willing to donate $250 million more to help Mr. Trump seek an unconstitutional third term.

Mr. Trump’s continued fund-raising is all the more striking given his boasts during his first presidential campaign a decade ago that he was an outsider whose personal wealth made him impervious to Washington’s pay-to-play politics and the manipulation of major donors, including Dr. Adelson’s late husband.

Liz Huston, a White House spokeswoman, rejected the suggestion that donors were getting special treatment. She said in a statement that Mr. Trump’s “only motivation as the president of the United States is improving the lives of the American people and making our country greater than ever before.” Donors who support him “should be celebrated, not attacked,” she said.

Donors who received administration jobs, government contracts, partnerships and approvals

While the donations far exceed most Americans’ means, the sums pale in comparison to the contracts being sought from the Trump administration.

Take Mr. Trump’s “Golden Dome” missile defense project, which could yield lucrative work for a number of contractors. Palantir has already held discussions about being involved. Firms including Lockheed Martin and Boeing also are expected to compete for pieces of the work; each company donated $1 million to Mr. Trump’s inaugural committee. That is the same amount they gave to President Joseph R. Biden Jr.’s inaugural committee.

But Lockheed Martin also donated $10 million to the Trust for the National Mall for Mr. Trump’s ballroom project and $5 million to America250, according to two people familiar with the sums. Lockheed is the primary maker of F-35 fighter jets, which cost about $80 million to $110 million each. While some national security officials have expressed concern about selling the jets to Saudi Arabia, Mr. Trump announced last month that he planned to approve such sales. The next day, Lockheed’s chief executive attended a black-tie dinner at the White House honoring Crown Prince Mohammed bin Salman of Saudi Arabia, which was also attended by executives for other defense contractors.

As for Boeing, two months after the inauguration, Mr. Trump announced that the company would be paid to build more than 180 new advanced fighter jets for the Air Force.

Major defense contracts can take years to develop, bid and execute, and there is no evidence that any such contracts were awarded as a direct result of donations.

Boeing’s ability to pursue federal contracts could have been hindered by criminal charges stemming from two fatal crashes of its planes during Mr. Trump’s first term. But this year, the Trump Justice Department dropped the case, entering into a settlement that required the company to improve its safety and compliance programs and pay hundreds of millions of dollars into a fund for victims.

Presidents have long awarded their campaigns’ top donors with ambassadorships, jobs and appointments to boards and commissions. Mr. Trump appears to have taken that tradition to a new level, tapping at least 32 people for an array of positions — including in his cabinet — who have donated at least $250,000 each to his causes after the election, or whose companies or families have made such donations.

Among them is Howard Brodie, now the U.S. ambassador to Finland. His parents, Elizabeth and Stefan Brodie, donated to the Trump inauguration, MAGA Inc. and the ballroom project after Mr. Trump’s victory in the 2024 election. The elder Brodies were invited to the White House dinner last month honoring the Saudi crown prince, and Stefan Brodie attended a dinner the month before for major donors who gave at least $2.5 million for the ballroom.

Another Trump ambassador nominee, the Miami mortgage lender Bernie Navarro, gave a little-noticed $1 million donation to the inaugural committee through an obscure company registered in Puerto Rico. Mr. Navarro, a close ally of Secretary of State Marco Rubio, said in a statement that the donation was unrelated to his interest in becoming an ambassador. “In retrospect, he is doing such an amazing job that I wish I would have done more,” Mr. Navarro said of Mr. Trump.

In all, more than a dozen donors have been nominated or confirmed for ambassadorships.

It is not possible to definitively link donations to nominations.

Tommy Pigott, a spokesman for the State Department, in a statement called Mr. Trump’s ambassadors “an America first diplomatic A-team,” adding that they “were chosen to help drive forward historic wins for the American people, and they have done exactly that.”

Four of Mr. Trump’s cabinet officials made personal or corporate donations of more than $250,000.

They include Kelly Loeffler, the administrator of the Small Business Administration. She and her husband, Jeffrey C. Sprecher, the chief executive of the parent company of the New York Stock Exchange, donated a combined total of $11 million to groups Mr. Trump favors, including $1 million to the inaugural committee and $5 million to MAGA Inc., as well as previously unreported donations totaling $5 million for the ballroom, according to records and a person familiar with the fund-raising.

Donors who received pardons, relaxed enforcement and other relief