Younan, 58, came to the region in 2006 and oversaw the expansion of the Wall Street bank's presence and franchise in MENA with offices in Dubai, Doha and Riyadh. He will retire by the end of the year, the memo said.

Goldman has advised on some of the top deals in the region, including Saudi Aramco's $29.4 billion initial public offering last year.

It also advised Saudi Arabia's Riyad Bank on a potential merger with National Commercial Bank, though the plan was abandoned at the end of last year.

Goldman has appointed Fadi Abuali and Zaid Khaldi as co-chief executive officers for the MENA region, effective Jan. 1, in addition to their existing responsibilities in asset management and investment banking respectively, a separate memo said.

Khaldi will relocate to Dubai and Abuali will remain in London, but will split his time between London and Goldman's offices in the MENA region, the memo said.

Saudi Arabia has in recent years become one of the Middle East's biggest markets for bankers, who are keen to grab a slice of its active equities market as companies tap into Saudi investors' demand for shares.

The kingdom is encouraging more companies to list in a bid to deepen its capital markets under reforms aimed at reducing its reliance on oil.

(Reporting by Saeed Azhar; Editing by Louise Heavens and Jan Harvey)

By Saeed Azhar