Deutsche Bank turned over President Trump's financial records to Manhattan District Attorney Cyrus Vance through a subpoena filed last year.
On Wednesday, New York AG Letitia James said she will make a "major national announcement" at 11:30 a.m. on Thursday, Aug. 6.
Prosecutors have pored over Trump's financial records after the bank complied with the subpoena, the New York Times reports.
Vance and James, both Democrats, are investigating potential crimes in the U.S. president's financial dealings. Trump obtained loans from Deutsche Bank.
Vance launched an investigation into Trump's financial dealings last year after his former attorney, Michael Cohen, told Congress the president had a practice of misleading business associates and tax officials by undervaluing his assets.
As part of the investigation, Vance asked Trump's accounting firm to turn over 8 years of his tax returns, but they refused.
The U.S. Supreme Court ordered the tax returns released, but Trump's lawyers filed an appeal that will delay the release of the tax returns for at least another year.
Trump didn't seem concerned on Monday. "This is just a continuation of the witch hunt," he told reporters.
"It's Democrat stuff they failed with Mueller they failed with everything. They failed at every stage of the game. Even before I got in this was starting with the Mueller deal. Mueller started a little bit after," Trump said, correcting himself.
"It's a terrible thing that they do. It's really a terrible thing. The witch hunt has gone on long enough," he said.