The departure of UBS CEO Oswald Gruebel has exacerbated the fallout from the $2.3 billion loss the bank suffered from unauthorized trading less than two weeks ago.

“This is a bank now in disarray,” said Christopher Wheeler, an analyst at Mediobanca Securities SpA in London, which today cut its rating on UBS to “underperform” from “outperform.”

“The board made a terrible blunder” by not persuading Gruebel to stay, he said.

Gruebel’s departure has also taken a heavy toll on the already low morale within the investment-banking division, according to an executive at the unit who requested anonymity because he wasn’t authorized to speak publicly.