He has been boss of the global banking giant since 2019 and will remain so for up to a year while a replacement is sought.

The bank said it had begun the process of finding his successor and hoped to make an appointment in the second half of the year.

Mr Quinn, who has been with the bank for 37 years, said: “After an intense five years, it is now the right time for me to get a better balance between my personal and business life. I intend to pursue a portfolio career going forward.”

He said he made the decision after taking some time out over Christmas.

He said: “It’s been a phenomenal 37 years with the bank, but in that 37 years I haven’t had much of a break. This is a chance now to have a break.”

Matt Britzman, equity analyst, Hargreaves Lansdown, said: “Change at the top usually causes a wobble, more so when it's unexpected, and this does raise some questions about how the strategy will evolve from here. The HSBC portfolio is going through a reshuffle, and Quinn’s far from completing his mission to get costs under control.”

Mr Quinn said that the next phase for HSBC will be a “multi-year journey” and that now is a “natural transition point for the bank” and a “natural transition point for me.”

The bank reported pre-tax profits fell nearly 2% to $12.7bn (£10.1bn) in the first quarter as a hit from the sale of its Argentina business was offset by a gain from offloading its Canadian business earlier this year.

The group announced new share buybacks of $3bn (£2.4 billion) and a 31 cents (24.7p) a share dividend, including a first interim dividend of 10 cents (8p).