As the dust started to settle after the deadly 6 January Capitol attack in 2021, Donald Trump found himself losing corporate allies.

Shocked by the rampage that followed efforts to overturn the US presidential election, companies at home and abroad were suspending political donations and reviewing their ties with the outgoing leader. Even Deutsche Bank – which had propped up the Trump Organization for two decades – decided it would no longer do business with the disgraced politician.

But as Deutsche’s support fell away, one midsized California-based bank was ready to fill the financial vacuum.

Axos Financial has since become one of Trump’s biggest financial backers. With its biggest individual shareholder – the sub-prime auto king and billionaire Don Hankey – the NYSE-listed company has helped extend more than $400m (£318m) in loans to the returning president and his companies.

And investors are betting that Axos will thrive under the returning president, having pushed shares to a record high above $80 after the November US presidential election.

Axos was one of the first digital banks in the US, founded at the peak of the dotcom bubble at the turn of the millennium. Then known as the Bank of Internet USA (BoI), it offered customers 24/7 online access to their bank accounts, even on holidays: a point illustrated by its launch on US Independence Day on 4 July 2000.

After weathering the storm of the 2007-08 financial crisis, BoI embarked on a series of acquisitions under the president and chief executive Gregory Garrabrants, who helped expand the bank’s operations into clearing and investments.

Since Garrabrants took the reins, the group’s assets have soared to $36bn from just over $1bn, while profits have hit a record high every year since 2012. And the 53-year-old McKinsey and Goldman Sachs alumnus has been handsomely rewarded along the way.

Despite holding just a fraction of JP Morgan’s $3.7tn worth of assets, Garrabrants briefly eclipsed the pay of its famously high-paid boss Jamie Dimon with a $34.5m payout in 2018.

Axos stressed that the sum included the potential value of future share-based bonuses, would take several years to vest, and could not be compared “apples to apples” with other bank executives.

Garrabrants’ total pay has since fallen to $10.6m, but he remains one of the 10 highest-paid bank bosses in the US.

It has not all been plain sailing. The lender fought a series of legal battles with former staff and contractors, and came under investigation by the US regulator the Securities and Exchange Commission (SEC) for two years from 2015 over alleged conflicts of interests, and auditing practices.

Axos said it all stemmed from a smear campaign that involved “hit pieces” and “baseless allegations” being posted online from 2015, which formed the basis of “anonymous and wholly fraudulent complaints” made to regulators. It claims this was done “in the hope of instigating investigations, the existence of which the short-sellers could then use to create further doubts regarding the company and a decline in the company’s stock price”.

The SEC investigation was closed without enforcement action in 2017, shortly before the bank rebranded as Axos in 2018.

The group said its largest customers include the world’s leading hedge funds and private debt funds, which are “extremely well banked by larger and smaller competitors”. But Garrabrants – who told Bloomberg that discriminating against customers for their politics “undermines the fabric of our civil society” – has made headlines for offering services to customers that might cause other lenders to pause.

Axos temporarily held funds linked to Free Speech Systems, the media company run by the far-right conspiracy theorist Alex Jones. Jones filed for bankruptcy in 2022 after owing $1.5bn to parents over conspiracy theories he spread about the 2012 Sandy Hook school massacre. Axos said the account was opened through its bankruptcy services division on behalf of a court-appointed receiver. It shut the accounts last year, citing a series of unauthorised transactions.

It has also made forays into riskier arenas, temporarily offering accounts to cryptocurrency firms such as Binance US, whose parent company has been accused by the SEC of operating an “elaborate scheme to evade US federal securities laws”. Binance has said the SEC’s action was “unjustified”. Axos said it had no remaining business with any cryptocurrency company.

Meanwhile, Trump, who remains a customer, turned to Axos as he was facing looming deadlines to repay loans on Trump Tower and his Trump National Doral hotel and golf resort in Miami. Axos ended up offering $225m to the then ousted president in 2022, shortly before the loans fell due.

The chief executive’s support clearly made an impression on the Trump family, including the incoming president’s son, Eric Trump, who has said he is “honoured to call Greg a friend”.

An Axos spokesperson said the Trump Organization has been a “model borrower, meeting all its obligations in a highly professional manner”.

Help was also extended by Hankey, who himself made his fortune selling high-interest car loans to people with bad credit histories.

One of Hankey’s companies, Knight Specialty Insurance, posted a $175m bond that Trump needed in order to block a large civil fraud judgment while he tried to appeal against a $454m court ruling, in which he was accused of defrauding bankers and insurers by lying about his wealth.

Further support has been given though political donations. Hankey made $80,000 in political donations to Trump and the US Republican party in 2016, and Garrabrants’ donations have included $4,800 to Trump in 2020.

But despite Axos’s consistent profit growth, not everyone is cheering about its success. In June, the short-seller investment company Hindenburg Research accused the group of lax underwriting standards, and major issues with its portfolio of loans.

It said Axos was exposed to the riskiest asset classes, including commercial real estate, which its peers had rowed back on, while alleging that its customer base included “borrowers who couldn’t get loans from other banks”, resulting in problem loans.

Axos strongly denied the allegations. “The Hindenburg statement is false,” an Axos spokesperson said, adding that the company had an “exceptionally strong track record in its commercial real estate lending portfolio sustaining some of the lowest loss rates in the banking industry”.

They added: “The report has also been proven wrong by the passage of time as many of the loans cited in the report have either repaid or, if not repaid, are performing.”

While shares initially tumbled on Hindenburg’s allegations, investors are clearly crawling back and betting on its prospective success.

Hankey did not respond to requests for comment.