Andrea Orcel, Bank of America Merrill Lynch's
Orcel will become joint head of UBS's investment bank, alongside Carsten Kengeter, a role that will re-unite him with UBS chief executive Sergio Ermotti, the former Merrill Lynch banker who took over from Oswald Gruebel late last year.
The departure is a blow for Bank of America, under pressure to fix its flagging performance, but a coup for the Swiss bank that is fighting to restore its fortunes after a debilitating $2 billion (1 billion pounds) trading scandal.
Fluent in four European languages and in his late 40s, Orcel is a 20-year Merrill Lynch veteran and the banker of choice for clients like Santander and Unicredit, according to bankers at other firms.
At the height of the crisis in 2008, Merrill Lynch paid him close to $34 million in stock and cash for his services.
He is effective, even ruthless, when it comes to getting things done. There is a good chance some of his clients will go with him (to UBS), said a banker who has worked across from Orcel on several deals.
He elicits a strong response from clients, they either love him or hate him.
Orcel helped steer Santander through the ill-fated split up of ABN Amro in 2007, the largest banking transaction in history.
While the deal pushed Royal Bank of Scotland and Fortis to near collapse, Santander agreed to sell ABN's Italian business for a hefty $13.2 billion to Banca Monte dei Paschi before it had even taken control of the asset.
This year, Orcel sold Belgian lender KBC's
He had been touted as a candidate for Unicredit chief executive before the appointment of Federico Ghizzoni.
Brother Riccardo Orcel was a top executive at BAML until last year, when he left a job running investment banking for central and eastern Europe, the Middle East and Africa to join Russia's second biggest lender VTB
Andrea Orcel worked on VTB's privatisation last year, a deal worth $3.3 billion.
Sergio Ermotti, who worked at Merrill Lynch from 1987 to 2005, is overseeing the return of UBS to its Swiss roots, the comparatively conservative and stable-profit businesses related to private banking.
The future of Kengeter, a Gruebel contemporary, has been widely questioned since the trading scandal last year, which also claimed equities co-heads Francois Gouws and Yassine Bouhara.
Sergio knows Orcel very well, it is normal for a new chief executive to want to bring in people he is close to and has worked with before, a second person said. This is a great hire. Orcel is a relationship man, not a manager.
It is likely that UBS corporate finance bosses Simon Warshaw and Matthew Grounds will report into Orcel as well as Kengeter when he joins the bank.
Carsten has a trading background and Andrea is focused on relationships with clients, there should be a natural fit, a third person said.
Bank of America has raided UBS for some big hires when it was vulnerable, poaching equities and Asia specialist Matthew Koder last year.
But the firm is under pressure from investors to improve performance after the bank lost money in four of the last six quarters and its stock had fallen by half this year.
A BAML insider said it was not surprising to see senior people leaving as the restructuring is enacted.
Andrea is a very key person so it's not great for us, the person said.
BAML and UBS declined to comment. Orcel was not available for comment.
(Additional reporting by Sarah White in London and Katharina Bart in Zurich; Editing by Steve Slater and Elaine Hardcastle)