Eleven of the nation’s largest banks announced Thursday that they would deposit a total of $30 billion into First Republic Bank as Wall Street and U.S. officials staged an emergency intervention aimed at quelling tremors in the financial sector.

Bank of America, Citigroup, JPMorgan Chase and Wells Fargo announced infusions of $5 billion each to First Republic, while Goldman Sachs and Morgan Stanley will each deposit $2.5 billion. The Wall Street move, which was coordinated in part by Biden administration officials, is aimed at stabilizing First Republic and sending a signal to depositors and global markets that the U.S. financial system is secure despite the failures last week of Silicon Valley Bank and Signature Bank.

“This show of support by a group of large banks is most welcome and demonstrates the resilience of the banking system,” said a joint statement by Treasury Secretary Janet L. Yellen, Federal Reserve Chair Jerome H. Powell, and Federal Deposit Insurance Corporation Chairman Martin J. Gruenberg and Acting Comptroller of the Currency Michael J. Hsu.

BNY Mellon, PNC Bank, State Street, Truist and U.S. Bank all also announced deposits at First Republic of $1 billion each.

Yellen discussed the idea of an injection of private capital for First Republic personally on a phone call with JP Morgan CEO Jamie Dimon, who went to work getting the banks to agree on the concept, said two people familiar with the matter, who spoke on the condition of anonymity to describe private deliberations. Yellen and Dimon both phoned multiple CEOs over the next few days as the plan cohered.

Federal officials held an additional phone call with CEOs and regulators on Thursday morning to confirm the details of the plan, and Yellen met in person with Dimon at the Treasury Department shortly before the measure was formally announced, the people said. Yellen closely coordinated on the stabilization measure with White House Chief of Staff Jeff Zients and White House National Economic Council Director Lael Brainard.

While the money for the deposits is coming from private firms, U.S. officials were closely involved in coordinating between the large banks, aiming to stabilize the system without increasing the burden on taxpayer, according to two people familiar with the matter, who also spoke on the condition of anonymity to reflect private deliberations.

“They’re trying to create a firewall to protect themselves from further angst about the banking systems and continued bank runs,” said Mark Zandi, an economist at Moody’s Analytics. “It’s about shoring up the weakest links in the banking system, and in so doing, inoculating themselves from the fire getting to them.”

Financial experts said the intervention represented one of the most sweeping moves in the modern history of U.S. banking – and coming just on the heels of last weekend’s move by the government to backstop deposits at SVB, it reflected the extent of concern both among senior federal officials and Wall Street executives about the stability of the industry.

First Republic’s stock price swung all week, raising the prospect that a third major U.S. bank could go down in less than a week following the implosions of SVB and Signature Bank. Federal officials hope the Wall Street intervention will put an end to the fears rippling through the system. But last weekend’s move – including the decision to create a new central bank lending program and backstop all uninsured deposits at SVB and Signature – failed to stamp out the tremors entirely.

“This is as large of a bank-to-bank intervention that we have seen, where you have one institution stepping in to help another institution,” said John Sedunov, a professor of finance at Villanova University. “We have not yet reached total failure meltdown stage, and this is an attempt to stop the bleeding before things get worse and you have more widespread panic.”

The move was announced Thursday shortly after Yellen faced numerous questions on Capitol Hill about the crisis measures already approved by the federal government in response to the banking crisis, where she told lawmakers that the financial system is sound.

News of the rescue plan sent stocks up. All three major indexes closed up more than 1% . First Republic, whose shares had been down by more than a third earlier in the day, closed up almost 10% . Regional bank stocks were mostly stable Thursday, closing slightly up. The giant Swiss multinational bank Credit Suisse also recovered somewhat from its losses on Wednesday after tapping an emergency fund that the Swiss central bank set up.

Appearing in front of the Senate Finance Committee earlier Thursday, Yellen gave her most detailed explanation to date of why federal authorities moved to protect all uninsured deposits at SVB .

Regional banks were on the mind of lawmakers in Washington, D.C. During one pointed exchange, Sen. James Lankford, R-Okla., pressed Yellen on whether banks in his state would have to pay more to the Federal Deposit Insurance Corporation to protect the deposits at SVB now backstopped by the federal government.

On Sunday, Yellen and other federal regulators promised to make whole all uninsured deposits at SVB through a fund that raises money from fees assessed on banks. The Biden administration has maintained that taxpayers will bear no cost for backstopping the deposits, but critics have pointed out that these fees are raised from levies on banks, which could lead to higher fees for customers everywhere.

Lankford also charged that the interventions had effectively encouraged customers to pull their deposits from community banks and move them to larger financial institutions where they were more likely to be protected by the kind of federal action authorized by the Biden administration.

“All banks make their revenue off rates and fees to account holders, which means every Oklahoman will pay higher fees on their bank,” Lankford said.

Yellen did not rebut Lankford’s charge but emphasized that authorities had to respond to avoid a worse panic.

“If we had a collapse of the banking system, that would have very severe effects on banks in Oklahoma that will also be threatened,” Yellen said.

Lankford also challenged Yellen to deny that SVB had a large number of Chinese companies that would see their money guaranteed by the insured deposit fund paid into by Oklahoma banks. Yellen responded: “Uninsured investors will be made whole in that bank, and I suppose that could include foreign depositors. But I don’t believe there’s any legal basis to discriminate against uninsured depositors.”

The exchange marked one of several between GOP senators and Yellen over the crisis at SVB and the federal government’s response to it.

Sen. Mike Crapo, R-Idaho, the top Republican on the Finance Committee, argued that inflation exacerbated by government spending policies forced the Federal Reserve to raise interest rates quickly, which in turn threw the balance sheets of some banks out of whack. Crapo was also the lead author of a 2018 bank deregulation bill that repealed some rules on banks the size of SVB and Signature Bank, the two that regulators closed over the weekend, although experts disagree over whether it played a role in the current crisis.

“Inflation played a key role in the recent bank failures, as rising interest rates and mismanaged interest rate risk led to a liquidity crisis,” Crapo said.

Sen. Charles E. Grassley, R-Iowa, added: “Bank failures this past week highlighted how fragile our economy is given rising interest rates.”

Asked if inflation had a role in the SVB collapse, Yellen acknowledged that the interest rate hikes led to a decline in the value of some of the bank’s holdings. She declined to answer a question from Crapo over whether the FDIC “slow-walked” negotiations to find a buyer for SVB due to political reasons. Semafor reported earlier this week that the FDIC shut the largest banks out of the bidding process, citing the FDIC chair’s criticism of consolidation in the industry.

Sen. John Thune, R-S.D., also asked whether federal banking regulators working from home, instead of in-person, could have contributed to officials missing the bank’s distress.

“It seems to me from a supervisory standpoint, if your job is to examine banks, it’s kind of something you have to be there to do,” Thune said.

Yellen also said much of the investigation into what happened at SVB would fall to the FDIC but that she would keep lawmakers updated.

The treasury secretary also faced pointed questions from Sen. Elizabeth Warren, D-Mass., who argued that the Federal Reserve had made it harder for federal regulators to spot and remedy the kinds of problems that led to the crisis at SVB.

Warren slammed federal regulators and congressional Republicans for pushing looser rules in 2018 for the banking sector.

“This is part of the Fed’s action that led to weaker regulation,” Warren said. “Congress handed Chair Powell the flamethrower he aimed at the banking rules.”

Warren also said that “stress tests,” designed to measure the financial stability of a bank, had been weakened by that 2018 law. But Yellen pointed out that SVB encountered a “liquidity” crunch, meaning it did not have enough cash on hand to meet its obligations. Yellen said stress tests were more important for measuring bank capital – a separate measure of the amount of safe assets held.