Shares in Britain’s four largest publicly traded banks fell sharply on Monday, erasing more than £18 billion from their combined market value amid investor concerns about prospective tax increases. The decline began during early trading as market participants grew uneasy over rising government bond yields and intensified later in the day following reports that top executives from Barclays, HSBC, Lloyds, and NatWest were summoned to meet Chancellor John Healey.

The meeting is scheduled for Tuesday ahead of Healey’s first budget announcement on October 28, prompting speculation that the chancellor may introduce higher levies on the banking sector. Barclays and HSBC each closed down 4.1%, Lloyds declined 4.5%, and NatWest dropped 5.4%. HSBC, due to its larger market capitalization, accounted for the majority of the value lost, with its market worth falling by over £10 billion to approximately £246 billion.

Banks are seen as potential targets for increased taxation given their strong profit margins, which have been bolstered in recent years by sustained higher interest rates. Both the Trades Union Congress and campaign organization Positive Money have advocated for a windfall tax on banks to help fund government initiatives addressing rising household living costs.

However, the banking industry has strongly opposed additional taxes, highlighting the sector’s already elevated tax burden relative to other businesses. Following the 2007-09 financial crisis, banks in the UK became subject to a corporation tax surcharge and a balance sheet levy unique to the industry. According to UK Finance, the sector’s official lobbying body, the overall tax rate on a representative corporate and investment bank in London stands at 46.5%, compared with 39.1% in Frankfurt and 27.9% in New York.

The Treasury declined to comment on the reported invitation for bank executives to meet with Chancellor Healey. A senior banking executive described the call for the meeting as intriguing but provided no further details.

If the government moves forward with higher taxes on banks, analysts suggest that increasing the existing 3% corporation tax surcharge would be the most straightforward approach. Recent data showed that revenues from this surcharge rose by 20% to £1.2 billion during the 2025-26 financial year, underscoring its potential as a significant fiscal lever.