Credit Suisse plans to borrow up to SFr50bn ($54bn) from the Swiss central bank and buy back about SFr3bn of its debt, in an attempt to boost its liquidity and calm investors a day after the bank’s share price plummeted.

The Swiss National Bank had said on Wednesday it was willing to provide a liquidity backstop to Credit Suisse after the troubled lender’s shares fell as much as 30 per cent.

The sell-off came after the chair of Saudi National Bank, a major Credit Suisse shareholder, ruled out any further investment. It also followed turbulent trade in global banking stocks in the wake of Silicon Valley Bank’s collapse.

In a statement on Thursday, Credit Suisse said it had taken the decision “to pre-emptively strengthen its liquidity” by borrowing the funds from the Swiss central bank under a loan facility and short-term liquidity facility.

It plans to make a cash tender offer for 10 US dollar-denominated senior debt securities worth up to $2.5bn and four euro-denominated senior debt securities worth up to €500mn. The offers will expire on March 22.

Chief executive Ulrich Körner said the measures “demonstrate decisive action to strengthen Credit Suisse as we continue our strategic transformation”. Körner’s restructuring has included selling off a part of Credit Suisse’s investment bank and cutting thousands of jobs.

“My team and I are resolved to move forward rapidly to deliver a simpler and more focused bank built around client needs,” added Körner, who was appointed chief executive in July.

The move is the latest attempt by Credit Suisse to regain investor confidence after a series of scandals and setbacks rocked the Swiss bank and pushed its stock price to a record low.

Credit Suisse shares closed down 24.2 per cent on Wednesday, pushing its market value below SFr7bn. Shares in the bank, which raised SFr4bn of capital just a few months ago, are down 39 per cent this year and 85 per cent over the past two years.

The sell-off in Credit Suisse shares on Wednesday weighed on bank stocks in Europe and the US, which are also reeling from the closure of SVB, the biggest US bank failure since 2008. Its implosion came after long-dated Treasury bonds it had invested in collapsed in value.

Investors said Credit Suisse’s problems were a reminder that Europe’s banks also had large bond portfolios, the paper value of which has been hammered by rising interest rates.

For Credit Suisse, the latest share price drop added to what has already been a challenging week. On Tuesday, the bank revealed that its auditor, PwC, had identified “material weaknesses” in its financial reporting controls, leading to the delay of the publication of its annual report.

On Wednesday, Saudi National Bank chair Ammar Alkhudairy said “the answer is absolutely not” when asked if SNB would be open to providing capital to Credit Suisse. SNB bought a 10 per cent stake in Credit Suisse last year.

He said owning a large share of the bank would result in unwanted regulatory requirements, though he added he supported Credit Suisse’s restructuring plan and did not think it needed more capital.