UBS announced its takeover of Credit Suisse, Switzerland's second-largest bank, earlier this month. Credit Suisse's shares fell sharply during unrest in the stock markets caused by the collapse of several regional banks in the United States. "Integrating Credit Suisse is UBS's single most important task, and I am confident that Sergio will successfully guide the bank through this next phase," Hamers said. "I am, of course, sorry to leave UBS, but circumstances have changed in ways that none of us expected. I am stepping aside in the interest of the new combined entity and its stakeholders. It has been a pleasure and privilege to lead this great bank to where it is today." UBS chairman Colm Kelleher called Hamers "an outstanding CEO of UBS," saying the Dutchman brought the bank unprecedented success in a challenging environment.