Both UBS and Credit Suisse have significant investment and wealth management operations in the UK.

The combined entity will now operate as consolidated banking group and today marks the last trading day of Credit Suisse shares on the SIX Swiss Exchange.

The two banks jointly employ 120,000 worldwide, although UBS has already said it will be cutting jobs to reduce costs and take advantage of synergies.

The merger brings to an end Credit Suisse's 167-year history, hits in recent years by scandals and losses.

A series of problems in the last year caused a crisis of confidence in the bank’s future.

The “emergency rescue deal” was announced in March and the FCA said then it was “minded” to approve the deal in the UK.

As announced on 19 March, Credit Suisse shareholders will receive 1 UBS share for every 22.48 Credit Suisse shares held.

The UBS Group will manage two separate parent banks – UBS AG and Credit Suisse AG. Each institution will continue to have its own subsidiaries and branches, serve its clients and deal with counterparties.

UBS announced the new board of directors for certain Credit Suisse entities. Subject to regulatory approval, the Credit Suisse AG board will consist of Lukas Gähwiler (chair), Jeremy Anderson (vice-chair), Christian Gellerstad (vice-chair), Michelle Bereaux, Mirko Bianchi (until 30 June), Clare Brady, Mark Hughes, Amanda Norton and Stefan Seiler.

Colm Kelleher, UBS Group chairman, said: “I‘m pleased that we’ve successfully closed this crucial transaction in less than three months, bringing together two global systemically important banks for the first time.

“We are now one Swiss global firm and, together, we are stronger. As we start to operate the consolidated banking group, we’ll continue to be guided by the best interests of all our stakeholders, including investors. Our top priority remains the same: to serve our clients with excellence.”

Sergio P Ermotti, chief executive of UBS Group, said: “Today we welcome our new colleagues from Credit Suisse to UBS. Instead of competing, we’ll now unite as we embark on the next chapter of our joint journey.

"Together, we’ll present our clients an enhanced global offering, broader geographic reach and access to even greater expertise. We’ll create a bank that our clients, employees, investors and Switzerland can be proud of.”

UBS said it expects its CET1 capital ratio to be around 14% in the second quarter of 2023 and to remain around that level throughout 2023. It anticipates that Credit Suisse’s operating losses and significant restructuring charges will be offset by reductions in risk-weighted assets (RWA).