Michael Zink has been with the firm for more than 28 years, and was appointed Citi country officer for Singapore in April 2010. He became head of Asean in February 2012.

At the age of 57, he is one of the longest-serving country heads in Singapore. Citigroup Asia chief executive officer Francisco Aristeguieta told staff in a memo yesterday that “Michael has decided that now is the right time for him to return to the United States”.

He said that Zink “will ensure a smooth transition” as the bank starts the process to fill the “two vital roles” of Asean head and Singapore country officer.

Citi said a successor will be announced in due course. Zink, who joined Citi in 1988 in New York as a corporate relationship manager, will be with the firm until around May.

Aristeguieta said Zink has contributed significantly to the success of the franchise, and “his career epitomises the opportunities our global network provides for those who truly live our leadership values”.

Over the course of his Citi career, Zink worked in 10 countries, including Russia, Australia, South Korea, China and Indonesia. Aristeguieta said: “He has never shied away from challenging roles, and has always championed productive and innovative change.”

Zink was also lauded for his focus on promoting talent, having “recruited and developed a generation of leaders at Citi”.

Apart from his role at Citi, he is also co-chair of the Financial Services Committee and sits on the board of the US-Asean Business Council. He is a member of AmCham Singapore’s board of governors, and serves as a council member of the Association of Banks in Singapore.