Shares in Credit Suisse plunged on Monday as fears mount over the financial health of the Swiss bank.
Its shares fell by more than 10%, after the bank's boss failed to reassure investors – but later bounced back.
Last week, chief executive Ulrich Koerner insisted in a memo to staff that Credit Suisse's financial position was solid.
It comes ahead of a restructuring plan due when the bank reports results at the end of October.
Sources close to the bank confirmed a report in the Financial Times that executives at the Swiss bank spent much of the weekend seeking to calm key stakeholders about its financial strength.
A Credit Suisse spokesperson refused to comment.
In last week's memo, Mr Koerner told staff: "I trust that you are not confusing our day-to-day stock price performance with the strong capital base and liquidity position of the bank."
He said there were "many factually inaccurate statements being made" in the media, but urged staff to stay committed ahead of the transformation plan, which will be unveiled on 27 October.
"We are in the process of reshaping Credit Suisse for a long-term, sustainable future – with significant potential for value creation.
"I am confident we have what it takes to succeed."
Shares in Credit Suisse have been sliding over the past year amid fear's over the bank's financial position.
In July, the bank announced a strategy review and replaced its chief executive, Thomas Gottstein, with Mr Koerner, an asset management expert.
Credit Suisse has a major hub in London and employs 5,500 people in the UK.
According to Reuters, the Bank of England is monitoring the situation together with the Swiss regulator, FINMA.
The Bank of England declined to comment.
The chief executive of Credit Suisse insists the bank is as solid and stable as the Matterhorn. The problem is, from the outside it isn't looking that way – and perceptions matter.
The bank has been battered by scandal. It lost billions due to the collapse of Archegos Capital Management, suffered further damage from lending to the failed finance company Greensill Capital, and was fined hundreds of millions for its involvement in a loan scandal in Mozambique.
Ulrich Koerner was brought earlier this year to implement a major overhaul of the investment banking unit. He's due to unveil his plans later this month.
But market moves suggest some investors believe the bank is running out of cash.
Mr Koerner claims all is well – and he has written to Credit Suisse staff to reassure them of the fact. The trouble is, that memo itself appears to have triggered further speculation about the health of the business.
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Credit Suisse shares hit by worries over financial health – BBC
