Prosecutors raided Germany's Deutsche Bank Tuesday, reportedly in connection with questionable securities trading maneuvers designed to help clients exploit tax loopholes. 

The strategy allows investors to claim certain tax rebates without actually paying the taxes in question, the Wall Street Journal reports. European authorities have been investigating the practice since last year, and American regulators have probed similar maneuvers at Bank of America.

The raid comes at a sensitive time for Deutsche Bank, which recently saw its two leaders abruptly announce their departure from the bank. The co-chief executives, Anschu Jain and Jürgen Fitschen, oversaw a period of flagging profits and persistent legal woes, including a record $2.5 billion settlement over the Libor interest rate manipulation scandal.

The bank stated that no employees had been involved in any wrongdoing, Reuters reported. Prosecutors in Frankfurt have declined to go into specifics, saying only that "wide-ranging investigative measures" were underway at Germany's largest lender. The investigation reportedly centers around the German private bank Sal. Oppenheim, which was purchased by Deutsche Bank in 2010. 

Sources close to the investigation told Reuters and WSJ that authorities were concerned with "cum/ex" trades, otherwise known as "dividend stripping," in which investors buy and quickly sell a stock at a crucial moment, allowing them to exploit a loophole related to dividend taxation.