UBS may be facing another showdown with shareholders at its AGM in May, as the Swiss investor foundation Ethos, a persistent thorn in the bank's side, again criticised the bank over generous bonuses handed out to top bankers while business performance remains mixed.

Ethos said other UBS shareholders should vote against new chairman Axel Weber's Sfr4m signing-on bonus at the AGM on May 3, as well as a proposed share-capital increase that would be used to finance employee remuneration.