By Liana B. Baker

(Reuters) - Longtime Credit Suisse Group AG <CSGN.S> investment banker David DeNunzio is leaving the Swiss bank to become global head of mergers and acquisitions (M&A) at Wells Fargo & Co <WFC.N>, according to people familiar with the matter.

DeNunzio was formerly the global chairman of M&A at Credit Suisse.

At Wells Fargo, DeNunzio will partner with Sam Farnham, an investment banker who will be promoted to become head of M&A in the Americas, the people added, requesting not to be named because the moves have not yet been announced.

Farnham was formerly head of middle market investment banking. John Laughlin, the former head of M&A, will become a vice chairman of M&A, according to the people.

Representatives from Wells Fargo and Credit Suisse declined to comment. Bloomberg first reported the news on Friday.

DeNunzio worked at Credit Suisse for more than 25 years and had been global chairman of M&A since 2012. He joined the M&A group of the First Boston Corp in 1989, a year before it was merged into Credit Suisse, after nine years at Kidder, Peabody & Co.

Wells Fargo, a San Francisco-based lender known for its retail banking business, is a relatively small player in investment banking compared to other U.S. giants JPMorgan Chase & Co, Citigroup Inc and Bank of America Corp.

It is bulking up its practice, however, and has started to land larger deals. In March, Wells Fargo was named sole adviser to TransCanada Corp on its acquisition of Columbia Pipeline Group, a deal worth $13 billion including debt, putting it on track for its biggest fees from a single deal since at least 2000, according to data from Thomson Reuters and Freeman Consulting Services.

Credit Suisse has seen several bankers depart in recent months. Last month it lost a managing director in New York who went to Goldman Sachs Group Inc <GS.N>, five bankers in San Francisco who joined Jefferies LLC and two in Chicago who were hired at Macquarie Group Ltd <MQG.AX>.

Credit Suisse has also hired several investment bankers, including Marco Chisari and Haidee Lee, who start in July, and Ray Raimondi who starts in August. Chisari will focus on technology M&A, Lee will be head of sellside M&A Americas and Raimondi will be head of global industrials M&A.

Jason Truman, a healthcare banker, started at Credit Suisse in February.

(Reporting by Liana B. Baker in San Francisco; Editing by Bill Rigby)