HSBC said late Sunday that chief executive John Flint is out and new leadership is needed to meet the bank’s challenges.

The surprise announcement, just 18 months after Flint was elevated to the CEO role, signals a potential change in approach at one of the world’s largest banks. With a market value of $159bn, the London- and Hong Kong-listed lender is worth more than Citigroup, even though its stock has fallen underFlint’s tenure.