The market's concerns about an impending banking collapse were allayed on Friday by a $30 billion lifeline for First Republic Bank, but a late decline in the troubled U.S. lender's share price revealed that investors were still concerned about sector cracks.

Injecting the money into the San Francisco-based bank on Thursday, large U.S. banks swooped in to save the lender, beset by a growing crisis brought on by the failure of two additional mid-size U.S. lenders over the previous week.

According to a source with knowledge of the matter, the deal was put together by influential figures like Jamie Dimon, CEO of JPMorgan Chase, Federal Reserve Chairman Jerome Powell, and U.S. Treasury Secretary Janet Yellen.

Less than a day prior, Credit Suisse, a Swiss bank, secured an emergency central bank loan of up to $54 billion to support its liquidity. After a turbulent week for banking stocks, those deals assisted in bringing some stability back to the world markets on Thursday and Friday.

Although First Republic's stock rose 10% at the close on the news of the rescue, its shares dropped 18% in after-hours trading after the bank announced it would suspend its dividend and revealed its cash position and the precise amount of emergency liquidity it required.

Analysts worry that a banking crisis is still very much a possibility despite the authorities' apparent eagerness to quickly address systemic risks.

"They will keep the money in the First Republic to keep it alive for self-interest... to stop the run on banks." Then they will take it away gradually, and the bank will play out a slow death," said Mathan Somasundaram, founder of research firm Deep Data Analytics in Sydney.

"Yellen was clear overnight that all bank deposits were protected, but the bank might not be there," he said.

According to a statement from the banks, the rescue involved some of the biggest names in U.S. banking, including JPMorgan Chase & Co., Citigroup Inc., Bank of America Corp., Wells Fargo & Co., Goldman Sachs, and Morgan Stanley.

Investors were taken aback by late disclosures about First Republic's cash position, even after the injection, and how much it and other companies relied on the Fed this month for support, even though the support has prevented an imminent collapse.

Data released on Thursday showed that American banks recently requested record amounts of emergency liquidity from the Fed, expanding the balance sheet of the central bank after months of contraction. More generally, concerns about contagion risks continue.

"I don't believe that a global financial crisis is at its height right now. In comparison to 2008, balance sheets are much better, banks are better regulated, "RBC Capital Markets' Karen Jorritsma, head of Australian equities, said. But the reality of the contagion risk worries people, which undermines confidence.

Authorities have made an effort to emphasize that the current turmoil is different from the global financial crisis that occurred 15 years ago and is confident that the banking system is resilient.

The European Central Bank pushed ahead with a rate increase of 50 basis points on Thursday, claiming that banks in the eurozone were in good shape and that the change to higher rates should increase their margins.

The Fed's policy decision next week and whether it will continue with its erratic interest rate hikes will now be the main topic of discussion. Singapore, Australia, and New Zealand said they were keeping an eye on the financial markets in Asia but were confident in the strength of their local banks' capitalization and their ability to withstand significant shocks.

Since Silicon Valley Bank failed last week as a result of bond-related losses, banking stocks have taken a beating. As the first major international bank to accept an emergency lifeline, Credit Suisse sparked concerns about contagion and cast doubt on the ability of central banks to maintain swift rate increases. By Thursday, the focus had shifted to the US as major banks strengthened their backing for regional lender First Republic.

Rapid rate increases have made it more difficult for some businesses to service or repay loans, raising the risk of loss for lenders who are already concerned about a recession.

Thursday's closing price for Credit Suisse shares was 19% higher, offsetting some of Wednesday's 25% decline. According to data from Refinitiv, European banks have lost about $165 billion in market value since March 8.