After his numerous bankruptcies, Wall Street banks were leery of loaning money to Donald Trump. He then turned to Deutsche Bank who gave him a large loan. In the 2008 financial meltdown, Trump was unable to meet a 40 million dollar repayment. He sued Deutsche Bank for 3 billion dollars charging that they were part responsible for the meltdown and his misfortune. They settled and his loans were transferred to the private wealth division of Deutsche Bank.

Deutsche Bank has been charged with money laundering for Russian entities paying 600 million dollars in penalties to US and British regulators.

There are rumours that Donald Trump is involved with Russian money laundering through Deutsche Bank. That's why he refuses to release his tax returns. It's why he may fire Robert Mueller if his investigation starts poking around the Trump family finances.