James Dimon, known as Jamie, is an American billionaire businessman and financial executive. He became chief executive officer (CEO) of JPMorgan Chase & Co. (JPM) in 2006 and chairman of the firm in 2007. Under Dimon’s leadership, JPMorgan Chase has become the largest U.S. bank by consolidated assets and the largest bank in the world by investment banking revenue.

JPMorgan Chase is consistently ranked among the top banks in the world by market capitalization and other metrics as well. Dimon was previously on the board of directors of the Federal Reserve Bank of New York. He is also known for his key roles in building up Citigroup Inc. (C) and Bank One, the latter of which was acquired by JPMorgan Chase in 2004.

Early Life and Education

Jamie Dimon was born in New York City in 1956 to a family of finance and banking professionals. He has cited his grandfather, a Greek immigrant who was a stockbroker at Shearson, Hammill & Co., as a key influence in his early life.

Dimon attended the prestigious Browning School in New York City and Tufts University outside of Boston, eventually majoring in economics and psychology. He famously became a protégé of legendary finance executive Sandy Weill when Dimon wrote a thesis about the older financier.

After briefly working at Boston Consulting Group, Dimon matriculated at Harvard Business School. He pursued and obtained a Masters of Business Administration (MBA) degree and was in the same class as hedge fund managers Seth Klarman and Steven Mandel, among other notable business leaders. Dimon graduated in the top 5% of his class as a Baker Scholar.

Notable Accomplishments

After graduating Harvard, Dimon turned down offers at numerous large firms to take a position at American Express Co. (AXP) with his mentor Sandy Weill. He subsequently left American Express along with Weill and became chief financial officer (CFO) and, later, president of Commercial Credit.

One of Dimon’s most notable accomplishments is the massive transformation of Commercial Credit that he executed with Weill. Under his leadership, Commercial Credit made a significant number of acquisitions, including buying Primerica Corp. in 1987 and The Travelers Corp. in 1993.

Dimon’s role continued to transform as the company grew. He served as president and chief operating officer (COO) of Travelers in the 1990s while also acting as COO of Smith Barney Inc., Travelers’ subsidiary. He later became co-chairman and co-CEO when Smith Barney and Salomon Brothers combined. In 1998, after years of expansion, Travelers Group combined with major finance firm Citicorp. and formed Citigroup, with Dimon as the president of the new company.

In a surprise move, Weill fired Dimon from Citigroup in 1998 after the two had worked together for well over a decade. But Dimon rebounded quickly. In 2000, he became chairman and CEO of Bank One. Within just four years, he guided the company’s stock to climb by 59%, close to triple the growth of the S&P 500 over the same period.

JPMorgan Chase purchased Bank One in 2004, and Dimon became president and COO of the combined company at that time. But just three years later, he was chairman and CEO of JPMorgan Chase, and he has served in these roles since that time.

Shortly after Dimon assumed leadership of JPMorgan Chase, the 2007-2008 financial crisis began. Dimon deftly led his firm through the crisis, having already sold $12 billion in subprime mortgages in 2006. In the midst of the crisis, JPMorgan expanded rapidly, buying Bear Stearns—once valued at nearly $12 billion—for just $260 million, and WaMu for $1.9 billion. In the process, JPMorgan Chase became the biggest bank in the U.S.

Besides his work with JPMorgan, Dimon is also well known for his role on boards and as a financial advisor. He has advised President Obama and was rumored to be a candidate for President Trump’s Treasury secretary. Besides the Federal Reserve Bank of New York, Dimon has served on boards including those for the Business Roundtable, Bank Policy Institute, and Harvard Business School. He is also a member of the Financial Services Forum and Council on Foreign Relations.