John S. Koudounis

John S. Koudounis is an American business executive who currently serves as chief executive officer for Calamos Investments.Previously he was the president and chief executive officer for Mizuho Securities USA Inc., a subsidiary of Japanese banking holding company Mizuho Financial Group. He is a regular commentator for television and financial news programs including Fox Business, CNBC, CNN, Bloomberg, and others. At 44 years of age, Koudounis was the youngest CEO of any Wall Street firm when he was appointed in 2010.

Koudounis sits on the board of the National Hellenic Museum and the Hellenic Initiative. He also serves on the leadership board of Concordia as well as the board of MSUSA, and is a member of the prestigious Bretton Woods Committee.

Koudounis was raised in Chicago. He attended Niles West High School in Skokie, Illinois where he was class president and played basketball and football. He was awarded several scholarships for football and decided to matriculate in the Ivy League.

Koudounis chose to attend Brown University in Providence, Rhode Island. Although he was originally pre-med, he double majored in International Diplomacy and Foreign Affairs and Economics, and played football at Brown. He also interned for the late Senator John Chafee and at Kidder Peabody, working in the office on Black Monday in 1987.

After receiving his degree from Brown in 1988, Koudounis obtained a position with Merrill Lynch where he began his financial career. Merrill Lynch had the most competitive program on Wall Street, choosing only nine undergrads worldwide and appointing them associates right out of college. Koudounis also worked for ABN AMRO North America where he was the company's head of fixed income. He spent a total of 12 years with ABN AMRO.

Koudounis began working for Mizuho Securities USA Inc. in 2008. He served as the executive managing director and head of fixed income, responsible for the firm's activities in trading, sales, and investment banking. In his first year at the company, his division earned more than the entire firm had in its entire history. In 2010, Koudounis was appointed president and CEO of the company. He also sat on the company's executive management committee, risk committee, and new product committee. When he became the company's CEO in 2010, he was the youngest CEO on Wall Street at the age of 44. As well as having direct management responsibilities in the Americas, he served on the management team in Tokyo for the global organization.

In early 2016, Koudounis was appointed CEO of Calamos Investments, a global investment management firm headquartered in Naperville, Illinois. Koudounis, whose appointment was effective Monday, April 4, 2016, leads the firm's business activities, including executing the firm's growth strategy and expanding the firm's global footprint.

Koudounis's career expands beyond that of a business executive. He is a public speaker and has given commentary for television and news media outlets including CNBC, Bloomberg Television, and Fox Business.

Koudounis is married and has two children, twin daughters.