Sergio Ermotti has been reappointed as chief executive officer of UBS Group AG (SIX:UBSG), the largest bank in Switzerland, to help supervise its compelled CHF 3 billion rescue of rival Credit Suisse.

Ralph Hamers will be replaced as CEO starting on April 5 by Ermotti, who previously led Switzerland’s largest lender for nine years until retiring in 2020. Hamers will continue to serve as an advisor.

According to a statement released by UBS on Wednesday, “The Board took the decision in light of the additional challenges and objectives facing UBS after the announcement of the acquisition.”

The organisation went on to say that Ermotti is the best person to lead the integration of Credit Suisse’s operations because of his expertise managing the company throughout the aftermath of the financial crisis in 2007–2008. UBS claimed that the 62-year-old strengthened the bank’s resilience by “placing its global wealth and asset management division.”

According to UBS, “He quickly changed the investment bank by reducing its footprint and achieving a fundamental culture change within the bank, which helped it to restore the trust of clients and other stakeholders.”

Ermotti is to resign from his current post as chairman of reinsurer Swiss Re AG (SIX:SRENH) after its annual general meeting the following month in order to move into the job at UBS.

Morningstar analysts characterised UBS’ move to reassign Ermotti as “surprising yet reasonable.” Nonetheless, the modification does underline the disruption to the bank’s own strategy that the acquisition will cause, they continued.

According to estimates, UBS may have to make thousands of job losses and struggle to prevent important employees from leaving to work for rival companies. As a result, folding in Credit Suisse is likely to prove to be very difficult. The merger of the two Zurich-based companies, according to chairman Colm Kelleher, is likely to be more significant than any transaction made during the financial crisis.

Shares in UBS gained as much as 3% in early European trading.