The asset value erosion at Silicon Valley Bank (SVB) triggered a spate of withdrawals from uninsured depositors, which in turn created a bank run and eventual collapse of the 16th largest bank in the US.
Credit Suisse shareholders will get 1 UBS share for every 22.48 Credit Suisse shares under the deal. The merger will be completed by the end of the year.
Earlier on Wednesday, Credit Suisse' shares plunged after Saudi National Bank, which was Credit Suisse's largest investor, refused to offer further financial assistance.
Panic gripped markets following the collapse of Silicon Valley Bank last week, with investors increasingly becoming sceptical of the safety of banking stocks.
The expansion comes after the lender suffered worse-than-expected global wealth outflows of 92.7 billion Swiss francs ($98.29 billion) in the fourth quarter.