Lukas Muehlemann

John Mack is leaving Credit Suisse Group next month after falling out with the board over whether the bank ought to pursue a merger.

The unexpected management shake-up came following a board meeting in New York on Thursday. It is combined with a simplification of the way the bank's businesses are organised and shifts the balance of power back to Zurich. It also signals that the bank is prepared to abandon the bancassurance model it adopted when Lukas Muehlemann was chief executive.