There has been change at the helm of the Chicago-headquartered global investment manager.

Calamos Investments, a global investment management firm headquartered in Chicago, IL, has appointed John Koudounis as chief executive.

Koudounis was most recently president and CEO of Mizuho Securities, USA.

John Calamos, founder of Calamos Investments and former CEO, will remain as chairman and global chief investment officer.

Besides its Chicago headquarters, Calamos also has offices in London, New York and San Francisco.