Grübel began his career at a White Weld & Co. joint venture with Credit Suisse in the 1970s. Before joining UBS, Grübel was at Credit Suisse from 1985 until 2007, leading the firm since 2003.

He was CEO of Credit Suisse Financial Services from 2002 to 2004 and was Co-CEO of Credit Suisse Group (with John J. Mack) from 2003 until 2004. Mr. Grübel was a member of the Credit Suisse Group Executive Board between 1997 and 2001 and again from 2002 to 2007. He became the sole CEO with the ousting of John Mack in 2004.

After he retired in May 2007, he still held a board position at the Winterthur Group insurance company (a part of AXA) from 2007 until 2009.

As chairman of the CEO position at UBS he made a promise that he will lead the bank back to the profit zone of 15 billion USDS in 2014.