Formerly president of UBS Group Asia Pacific, he stepped down in 2016 after nearly seven years in the position to take a sabbatical.

[3] Yoon studied electrical engineering at the Massachusetts Institute of Technology, where he graduated with a bachelor's degree in 1982 and with a Master in Management in 1986 from the MIT Sloan School of Management.

From June 2009 until November 2010, he served as CEO and Chairman of UBS AG Asia Pacific,[9] succeeding Rory Tapner.

[6][10] From November 2010 he held the position of co-CEO and co-Chairman,[9] and in March 2012 he was appointed again as sole CEO of UBS Group Asia Pacific.

[9] Yoon holds the position of Chairman of the Asian Executive Board for the MIT Sloan School of Management[9] and is a member of the advisory board of the MIT Golub Center for Finance and Policy.