The boss of a UK high street bank has told a panel of politicians that the possibility of a cyber attack "keeps me awake at night".
Ian Stuart, chief executive of HSBC UK, was one of a number of bank bosses speaking to the Commons Treasury Committee this week on a range of subjects.
But it was cyber-security that ranked as "top of the agenda" according to Stuart.
"It does worry me - we can be attacked and we are being attacked all the time," he said.
Over the last two years, nine major UK banks and building societies have jointly suffered a total of more than 800 hours of tech outages, equivalent to around 33 days. .
The most recent high-profile attack on a financial institution occured in February when four high street banks - HSBC, Lloyds, TSB and Nationwide - all suffered outages. More than 1.2 retail banking customers were affected.
And more recently, UK high street retailers were hit by a major cyber attack. Marks & Spencer was the hardest hit and was reported to be losing £43m a day in lost sales as it struggled to restore its services.
Stuart also spoke about the multi-million dollar investment HSBC and other banks have been forced to make in their IT security as a result of increased cyber risks.
"I think the amount of money banks - all of us - will be putting into our systems is enormous," he said. "The defence mechanisms you put in are absolutely critical."
HSBC was one of nine banks to be represented at the Committee hearing - Barclays, Lloyds, Nationwide, Santander, NatWest, Danske Bank, Bank of Ireland and Allied Irish Bank also provided evidence on the day.
The nine banks experienced 158 IT failures between them in the 26 months between January 2023 and February 2025.