The public prosecutor in Cologne is investigating two former managers of Hamburg Commercial Bank AG over alleged serious tax evasion, Handelsblatt reported Oct. 14.

The managers allegedly participated in illegal dividend stripping, which is the practice of buying shares shortly before a dividend is declared, known as cum dividend, and then selling them when the previous owner of the stock is entitled to the dividend, known as ex-dividend.

The two managers ran the cum-ex dividend scheme while Hamburg Commercial Bank, formerly known as HSH Nordbank, was being rescued by the state. The bank had run into trouble after the financial crisis because of soured loans in its shipping book.

With more than 130 banks suspected to have taken part in the illegal cum-ex trades, this is the largest tax scandal in Germany, Handelsblatt said.