For a while, people in Frankfurt's banking district had the impression that the drug dealers in the neighbouring railway station district had expanded their territory. Hardly a week went by without a police raid. But what was understandable in the case of the cum-ex transactions (though they were often difficult to prove), seemed strange in the case of the greenwashing allegations against DWS.

After almost three years, the public prosecutor's office has now ended its investigation, with a fine. However, the fine is quite something: 25 million euros is no small sum.

The public prosecutor's office has to consider the question of proportionality. But not because of the amount of the fine, which for the first time puts them on an equal footing with the US Securities Exchange Commission. Instead because of its reputation-damaging investigative methods. After all, Deutsche Bank's fund subsidiary was not being prosecuted for secretly greenwashing its products in some back room. It was being prosecuted for puffing out its cheeks too much in its public image when it comes to sustainability.

No files had to be seized from DWS to provide this evidence. Reading the relevant brochures and advertising material would have been enough. Even without raids, the investigation could not have been thwarted by shredding files. After all, the misleading advertising messages were aimed at the widest possible public, and ended up in the electronic mailboxes of tens of thousands of investors and providers.

However, the investigators in the DSW case also wanted to puff out their cheeks. As if the aim was to somehow outdo the self-promotion of whistleblower Desiree Fixler. This show-off by the self-promoters has not failed to have an effect. The uncertainty in the industry is likely to have contributed significantly to the drastic decline in newly launched sustainability funds. A reasoned debate would have been more helpful. About the limits of marketing, and the overdue introduction of fines that are high enough to deter impersonators.