GENEVA (AP) — Credit Suisse shares surged Thursday after the Swiss central bank agreed to loan the bank up to 50 billion francs ($54 billion) to bolster confidence in the country’s second-biggest lender following the collapse of two U.S. banks.

Credit Suisse announced the agreement before the Swiss stock market opened, sending shares up as much as 33 percent before they settled around a 17 percent gain, to 2 francs ($2.15), in late afternoon trading. That was a massive turnaround from a day earlier, when news that the bank’s biggest shareholder would not inject more money into Credit Suisse sent its shares tumbling 30 percent. The plunge in price dragged down other European banks and deepened concerns about the international financial system.

European banking stocks also rose modestly Thursday.

The Swiss National Bank said Wednesday that it was prepared to back Credit Suisse because it meets the higher financial requirements imposed on “systemically important banks,” adding that the problems at some U.S. banks don’t “pose a direct risk of contagion” to Switzerland.

Regulators are trying to reassure depositors that their money is safe. They “don’t want anybody to be the person who sits in a darkened room or darkened cinema and shouts fire, because that’s what prompts a rush for the exits,” said Russ Mould, investment director at the online investment platform AJ Bell.

Credit Suisse, which was beset by problems long before the U.S. bank failures, said the loans from the central bank would give it time to complete a reorganization designed to create a “simpler and more focused bank.”

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“These measures demonstrate decisive action to strengthen Credit Suisse as we continue our strategic transformation,” Chief Executive Ulrich Koerner said in a statement.

Despite the banking turmoil, the European Central Bank approved a large, half-percentage point increase in interest rates to try to curb stubbornly high inflation, saying Europe’s banking sector is “resilient,” with strong finances.

European Central Bank Vice President Luis de Guindos said at a news conference that European banks’ exposure to Credit Suisse is “quite limited.”

Higher rates fight inflation but in recent days have fueled concern that banks may have caused hidden losses on their balance sheets.

Central banks in the U.S. and Europe have moved quickly to restore confidence after last week’s collapse of Silicon Valley Bank, the second-biggest bank failure in U.S. history.

American authorities moved quickly to guarantee all of the deposits of the California-based bank and the smaller Signature Bank of New York. The U.S. Federal Reserve also announced additional funding to ensure other banks could meet the needs of depositors.

In a similar move, the British government and Bank of England facilitated the sale of Silicon Valley Bank’s U.K. arm to HSBC, one of Europe’s biggest banks, ensuring that customers would have access to their money.

The rapid response is different from what happened at the start of the global financial crisis 15 years ago, when U.S. authorities allowed the investment banking giant Lehman Brothers to collapse.

The loans to Credit Suisse “should prevent a Lehman moment, much to the relief of markets and investors,” said Victoria Scholar, the head of investment at the online investment service known as Interactive Investor. “This is a bank that’s been around since 1865 and has been instrumental in supporting growth of the Swiss economy.”

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ECB President Christine Lagarde said the banks “are in a completely different position from 2008” during the financial crisis.

After that crisis, Europe strengthened its banking safeguards by transferring supervision of the biggest banks to the central bank.

“Crises are never exactly the same,” she said, “but the architecture of our banking system, the framework within which they operate, the supervision that is applied to the banking system, have been all considerably improved.”

Banks are under pressure after interest rates rose rapidly following a prolonged period of historically low rates.

To boost the return on their investments, banks needed to take more risks and some “did this more prudently than others,” said Sascha Steffen, professor of finance at the Frankfurt School of Finance & Management.

As a result, some banks now face a shortage of “liquidity,” meaning they cannot sell assets quickly enough to meet the demands of depositors.

Credit Suisse shares dropped to a record low Wednesday after the Saudi National Bank said it would not put more money into the Swiss lender to avoid regulations that kick in if an investor’s stake rises above 10 percent.

Credit Suisse also reported that managers had identified “material weaknesses” in the bank’s internal controls on financial reporting as of the end of last year. That fanned new doubts about the bank’s ability to weather the storm.

Its stock has suffered a long, sustained decline: Now trading for a little over 2 francs ($2.15), the stock was valued at more than 80 francs ($86.71) in 2007.

The Swiss bank has been pushing to raise money from investors and roll out a new strategy to overcome an array of troubles, including bad bets on hedge funds, repeated shake-ups of its top management and a spying scandal involving Zurich rival UBS.

Outside a Credit Suisse branch on Thursday, accountant David Glaus said the Swiss government is unlikely to let such a large bank fail, if for no other reason than to protect Switzerland’s banking industry.

“It remains a Swiss bank. In the background, there are people who will support and protect it because I don’t think it’s in our best interests for it to go bankrupt,” he said.

But he thinks the country has a fallback position to keep up appearances in case of the worst.

“We still have chocolate and cheese, anyway, to uphold our image,” he said.

Kirka reported from London. AP reporters David McHugh in Frankfurt, Germany, Colleen Barry in Milan and Joseph Krauss in Ottawa, Ontario, contributed.