Authorities had been scrambling to rescue Credit Suisse before financial markets reopened on Monday.

The agreement, announced late on Sunday, includes 100 billion francs ($108bn) in liquidity assistance for UBS and Credit Suisse from the Swiss central bank.

“With the takeover of Credit Suisse by UBS, a solution has been found to secure financial stability and protect the Swiss economy in this exceptional situation,” the Swiss central bank said.

The Swiss Financial Market Supervisory Authority (FINMA) said that there was a risk that Credit Suisse could have become “illiquid, even if it remained solvent, and it was necessary for the authorities to take action”.

To enable UBS to take over Credit Suisse, the federal government is providing a loss guarantee of a maximum of 9 billion francs ($9.7bn) for a clearly defined part of the portfolio, the government said.

This will be activated if losses are actually incurred on this portfolio. In that eventuality, UBS would assume the first 5 billion francs ($5.4bn), the federal government the next 9 billion francs ($9.7bn), and UBS would assume any further losses, the government said.

Credit Suisse, a 167-year-old bank, has been the biggest name ensnared in market turmoil unleashed by the recent collapse of United States lenders Silicon Valley Bank and Signature Bank, forcing it to tap $54bn in central bank funding last week.

Authorities had been scrambling to rescue Credit Suisse, among the world’s largest wealth managers, before financial markets reopened on Monday.

FINMA, which said it had approved the takeover, said recent measures to stabilise itself were “not enough to restore confidence in the bank, however, and more far-reaching options were also examined”.

UBS and Credit Suisse are both in a group of the 30 global systemically important banks watched closely by regulators, and Credit Suisse’s failure would ripple throughout the entire financial system.

The announcement came in a make-or-break weekend after some rivals grew cautious in their dealings with the struggling Swiss lender, and its regulators urged it to pursue a deal with UBS.

The two banks’ fortunes have diverged sharply over the past year. UBS earned $7.6bn in profit in 2022, while Credit Suisse lost $7.9bn. Credit Suisse’s shares are down 74 percent from a year ago, while UBS’s are relatively flat.