One of the great mysteries of the business world is why Deutsche Bank lent financial pariah Donald Trump $2 billion over two decades, when other firms treated him like an infectious disease capable of wiping out entire populations. Thanks to Democrats’ newly obtained subpoena power, the answer may be revealed through the “extensive internal documents and communications about Mr. Trump” the bank is expected to start handing over to congressional committees next month. In the meantime, however, a report from The New York Times about the president’s relationship with the German lender has shed some light on the matter. For one, Deutsche had a “ravenous appetite for risk,” including the risk of doing business with a guy whose name was synonymous in some quarters with bankruptcy. As a result, reporter David Enrich writes, bank executives were happy not only to ignore repeated, glaring red flags, but to go along with Trump’s cornucopia of financial lies.

Enrich brings the receipts. In 2004, shortly after Trump Hotels & Casino Resorts defaulted on hundreds of millions of bonds, causing steep losses for Deutsche clients, Trump asked the bank’s commercial real-estate group to lend him more than $500 million to build a 92-story skyscraper in Chicago. It did, but not before employees determined, among other things, that Trump was massively inflating his assets.

Mr. Trump told Deutsche Bank his net worth was about $3 billion, but when bank employees reviewed his finances, they concluded he was worth about $788 million, according to documents produced during a lawsuit Mr. Trump brought against the former New York Times journalist Timothy O’Brien. And a senior investment-banking executive said in an interview that he and others cautioned that Mr. Trump should be avoided because he had worked with people in the construction industry connected to organized crime.

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In patented Trump fashion, shortly before the bulk of the loan was due in November 2008, he sued the bank to get out of repaying, demanding $3 billion in damages and arguing that Deutsche had, in part, caused the financial crisis and was therefore to blame for his inability to sell hundreds of condo units. The firm countersued, and investment-banking executives severed ties with the real-estate developer. However, other divisions of the company were more than happy to go back for more.

Shortly after the Chicago lawsuit was settled, Jared Kushner was told that Mr. Trump was looking for a loan and introduced him to [private banker] Rosemary Vrablic, according to people familiar with the relationship.

Mr. Trump flew Ms. Vrablic to Miami to show her a property he wanted to buy: the Doral Golf Resort and Spa. He needed more than $100 million for the 72-hole property. Deutsche Bank dispatched a team to Trump Tower to inspect Mr. Trump’s personal and corporate financial records. The bankers determined he was overvaluing some of his real-estate assets by as much as 70 percent, according to two former executives.

But hey, what’s a few wildly inflated assets among friends? And speaking of friends, if Deutsche really wanted to show it was Trump’s friend . . .

Mr. Trump also expressed interest in another loan from the private-banking division: $48 million for the same Chicago property that had provoked the two-year court fight. Mr. Trump told the bank he would use that loan to repay what he still owed the investment-banking division, the two former executives said. Even by Wall Street standards, borrowing money from one part of a bank to pay off a loan from another was an extraordinary act of financial chutzpah. . . . A powerful committee in Frankfurt, which evaluated loans based on risks to the bank’s reputation, signed off.

By 2014, according to the Times, Deutsche was not only happy to go along with Trump’s alternative truths about his assets, but helped to aid and abet them:

In early 2014, Mr. Trump and his personal lawyer, Michael Cohen, approached Ms. Vrablic about more potential loans. The owner of the Buffalo Bills had died, and the N.F.L. franchise was up for sale. Mr. Trump was interested, and he needed to show the league he had the financial wherewithal to pull off a transaction that could top $1 billion.

Mr. Trump asked Ms. Vrablic if the bank would be willing to make a loan and handed over bare-bones financial statements that estimated his net worth at $8.7 billion. Mr. Cohen testified to Congress last month that the documents exaggerated Mr. Trump’s wealth. Deutsche Bank executives had reached a similar conclusion. They nonetheless agreed to vouch for Mr. Trump’s bid, according to an executive involved.

Trump’s bid did not win, but shortly thereafter, the bank lent him $170 million to renovate the Old Post Office building that would become the Trump International Hotel Washington, where foreign governments and other parties looking to kiss the ring are known to book rooms. Shortly after that, Trump was elected president, and the bank, realizing it had somehow “become the biggest lender to the president-elect,” reportedly uttered a collective dear god, what have we done?

A report prepared by the board’s integrity committee concluded that executives in the private-banking division were so determined to win business from big-name clients that they had ignored Mr. Trump’s reputation for demagogy and defaults, according to a person who read the report.

The review also found that Deutsche Bank had produced a number of “exposure reports” that flagged the growing business with Mr. Trump, but that they had not been adequately reviewed by senior executives.

According to the Times, managers started telling employees not to mention the word “Trump” to people outside the bank, out of fear of “stoking public interest in its ties to the new president.” Unfortunately, as the old saying goes, it was a little fucking late for that.

Two years after Mr. Trump was sworn in, Democrats took control of the House of Representatives. The chamber’s financial services and intelligence committees opened investigations into Deutsche Bank’s relationship with Mr. Trump. Those inquiries, as well as the New York attorney general’s investigation, come at a perilous time for Deutsche Bank, which is negotiating to merge with another large German lender.

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