Germany’s banking regulator is worried that the country’s biggest banks will continue to face expensive misconduct cases, according to the president of the watchdog known as BaFin.

“Part of the problem so far is you never know what is happening next week,” Felix Hufeld said in an interview in Frankfurt on Wednesday. “Another unexpected charge may pop up out of the blue.”

Banks are paying record fines for manipulating markets, helping some clients break the law and failing to adequately disclose financial risks. The expenses and associated increases in capital requirements have eroded lenders’ buffers and hurt profitability.

Germany’s big banks are sufficiently capitalized to deal with their legal risks “from what we can see,” Hufeld said, without specifying which ones.

Deutsche Bank AG, Germany’s biggest lender, has racked up more than 11 billion euros ($12.4 billion) of legal expenses, including reserves, since 2008 began, company and court filings show. That’s more than any other bank in continental Europe and the fifth highest in Europe when considering funds U.K. banks have set aside for customers who were sold loan insurance they didn’t need, calculations by Bloomberg show.

Hufeld said that Bafin’s investigation of alleged attempts to manipulate the $5.3 trillion per day currency market focuses on the euro and U.S. dollar.

“We are rather advanced actually in our examinations and hope to be finished within the next couple of months,” he said. “We have been surprised about the extent of misuse in that context.”

Regulators outside of Germany have fined seven banks from the U.S., U.K. and Switzerland a total of more than $10 billion in two rounds of penalties for their role in manipulating currency markets.

A spokesman for Deutsche Bank declined to comment on Hufeld’s remarks. The bank has said it is cooperating with regulators in their investigations of the foreign exchange market.

Hufeld said he wants to make sure banks avoid a repeat of the misconduct. “It is of paramount importance for those banks to fix their processes, their internal oversight processes,” he said.

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