The errant transfer occurred about a week before Easter as Deutsche Bank (DB) was conducting a daily collateral adjustment, the person said. The sum, which far exceeded the amount it was due to post, landed in an account at Deutsche Boerse’s Eurex clearinghouse.

The error, which took place in the final weeks of former Chief Executive Officer John Cryan’s tenure, was quickly spotted and no financial harm suffered. But the episode raises fresh questions about the bank’s risk and control processes, which Cryan had boasted of improving before his ouster.

“This was an operational error in the movement of collateral between Deutsche Bank’s principal accounts and Deutsche Bank’s Eurex account,” Charlie Olivier, a spokesman for Deutsche Bank, wrote in an emailed statement. “The error was identified within a matter of minutes, and then rectified. We have rigorously reviewed the reasons why this error occurred and taken steps to prevent its recurrence.”

It’s another misstep for Deutsche Bank at a time when it is undergoing a change of leadership in the wake of its third straight annual loss, and, like other lenders, faces increased scrutiny from regulators. Cryan, who was CEO for three years, said in a speech earlier this year that the bank was approaching the end of “phase 1” of his restructuring, which bolstered internal controls and shrunk the number of operating systems at the bank to 32 from 45.

Deutsche Bank shares, which have fallen 27% this year, fell 0.8% to 11.60 euros as of 9:28 a.m. Analysts at cross-town rival Commerzbank Thursday slashed their target price for the stock from 15 euros to 11, calling it the “cactus among investment banks” because it’s “spiky and slow growing.”

“A bank mistakenly making such a large transfer shows its controls aren’t working adequately, and it’s embarrassing,” said Dieter Hein, an analyst at Fairesearch who has the equivalent of a sell recommendation on the bank’s stock. “This kind of incident shows that the bank’s problems are so big that you can’t fix them immediately. Cryan failed.”

Hein also said chief operating officer, Kim Hammonds, who herself is being ousted, bears some of the blame given her involvement in Cryan’s information-technology revamp. Hammonds reportedly called Deutsche Bank “the most dysfunctional company” she’d ever worked for, and hasn’t denied making the remarks.

Bear Trap

The error should have been caught by an internal fail-safe system known as a “bear-trap,” the person said. The mechanism was set up after an internal audit at the bank triggered by an earlier collateral payments error, in March 2014, the person said.

While such errors do occur, the amount involved — more than the bank’s market capitalization of around 24 billion euros — is highly unusual, according to the person.

Eurex held back 4 billion euros of Deutsche Bank’s funds over the weekend of March 23, the person said. A spokesman for Deutsche Boerse said the company doesn’t comment on single transactions or client relationships.

Deutsche Bank’s new CEO, Christian Sewing, is seeking to turn around the worst-performing member of the Stoxx 600 banks index this year, with the company’s shares having fallen 26% to date. Analysts have said Sewing’s appointment raises questions about the lender’s future direction, especially the under-performing investment bank business.

In a separate development, Germany’s biggest bank has been asked by the European Central Bank to simulate an orderly wind-down of its trading book, Chief Financial Officer James von Moltke told Bloomberg Monday. Deutsche Bank is the first to receive such a request from the ECB, according to a person familiar with the matter, who said the ECB is using Europe’s largest investment bank as a “guinea pig” before it sends similar requests to other banks.

Deutsche Bank’s Chief Regulatory Officer Sylvie Matherat said in an interview with German media that the bank will bolster its department for compliance, regulatory issues and fighting corruption by another 400 people by year-end, making it 3,000-strong.