GLOBAL - Swiss shareholder groups Ethos and Actares are considering to join a US class action against Swiss bank UBS.

A city public pension fund in the state of Michigan filed a lawsuit against UBS in 2008, claiming the Swiss bank had failed to disclose bad investments in the US mortgage sector in 2007 and 2008.

Vinzenz Mathys, spokesman at Ethos, told IPE that joining the class action would be a "fiduciary duty" as a UBS shareholder.

"If the class action ends in a settlement, UBS and not the fallible managers will have to pay - which, in fact, means UBS shareholders not taking part in the class action will have to pay."

Actares is also considering joining the class action, but, like Ethos, the shareholder group stressed it was still uncertain whether European investors would be allowed to join.

Ethos said its board would decide whether to join the class action once it had been confirmed that European investors were allowed.

Roby Tschopp, director at Actares, added his shareholder group was still looking into the possibility of filing its own lawsuit against former UBS board members, rather than the bank itself.

UBS recently ruled out taking any legal action against former members of its board.