Matthew M. Riegner has been named chief financial officer at Boulder, Colo.-based Mix1 Beverage Co. Riegner joins the company after five years as director of corporate development, treasury and M&A at Englewood, Colo.-based CSG Systems International Inc. Bob Pinkerton, who has served as both chief executive officer and chief financial officer for Mix1, now will focus primarily on his role as chief executive.