By Geoffrey Smith 

-- (SIX:) stock leaped over 30% at the open in Zurich on Thursday, after the troubled lender a 50-billion-franc support line from the Swiss National Bank. 

By 04:15 ET (08:15 GMT), Credit Suisse shares in Zurich were up 33% at CHF 2.25 (CHF 1 = $1.0811).

The move reverses Wednesday's record drop in the stock, when Saudi National Bank (TADAWUL:), its largest shareholder, said it would not inject any further capital.

Saudi National Bank chairman Ammar Al Khudairy rowed back his comments later, telling CNBC that "Everything is fine. I don’t think they’ll need more capital.”

In a statement overnight, the SNB and regulator FINMA had asserted that Credit Suisse met all the required standards for capital and liquidity that apply to systemically important banks.

They said that there was consequently no risk of contagion to Credit Suisse from the volatility in the U.S. banking system, where three smaller lenders collapsed in the space of a week. 

In addition to the CHF 50B Covered Loan Facility, Credit Suisse also said it will buy back up to $2.5B and €500M (€1 = $1.0622) of bonds issued by its various operating companies. These have been aggressively sold in recent days and trade at a significant discount to face value. Buying them back at the current distressed rates and then retiring the bonds will generate an immediate profit for the bank, improving the bank's capital position. 

Credit Suisse said earlier this month that it expects to lose money in both its investment bank and its key wealth management division in the first quarter of this year, as it accelerates a thorough restructuring. It has lost some $9B over the past two years, wiping out all the profits made in the previous decade. 

The Swiss bank has long been designated by global regulators as one of the world's Systemically Important Banks, a so-called G-SIB. That means that it has to hold more capital and more liquid assets than institutions such as Silicon Valley Bank, Signature Bank or Silvergate Capital, all of which failed last week.  

At the end of the fourth quarter, its core tier 1 capital ratio - the benchmark measure for financial strength - stood at 14.4%, while its liquidity coverage ratio stood at 144%. The LCR is designed to ensure that banks can endure at least one month of abnormally high outflows. The Covered Loan Facility agreed with the SNB overnight will push its LCR up to around 200%, according to some estimates.