A year after he took the helm at Credit Suisse, Tidjane Thiam’s already-fraught attempt to revamp the Swiss bank faces a new hurdle: market turmoil sparked by the UK’s Brexit vote.

Exactly one year ago Friday, Thiam, a former consultant and insurance executive, became CEO of the bank, at a time it faced growing calls to curb its reliance on volatile, and costly, investment banking operations. In October, he unveiled a plan - later expedited - to scale back the investment bank by selling off assets such as complex debt instruments as quickly as possible.