Gassan is a Director at McKinsey and Company and is the Managing Partner for McKinsey's Saudi Arabia Office. He joined the Washington DC Office in 1997 and moved to the Middle East in 2000. Prior to joining McKinsey, Gassan was the Director of Strategy and Business Development at the WorldSpace Management Corporation.

Gassan leads the Public Sector Practice which focuses on areas of economic and social development and public policy. He has worked with the top leadership of several GCC countries on matters of economic reform and growth.
Gassan also co-leads the Energy Practice in the Middle East with a focus on upstream oil and gas. He advises leading GCC and European on large scale performance improvement and growth programs.

Gassan has written several articles for publications such as the World Economic Forum Middle East Summit as well as the McKinsey Quarterly, some of which are widely recognized and used as teaching tools in several Asian and European universities. He is also the recipient of many awards such as the National Achievement Award presented by the President of Yemen.

Gassan has a B.S. in Industrial Engineering from the Georgia Institute of Technology. In addition, he has a M.S. in Operations Research from MIT and an MBA in strategic management from the Sloan School of Management, MIT, both with highest honours.