Jay Mueller, the chief economist at Strong Capital Management, has officially replaced Brad Tank as head of fixed income. His new role ends speculation as to whether Tank, who left the firm at the end of July, will be replaced internally. Mueller will report directly to Dick Strong, chairman of the Menomonee Falls, Wis.-based asset management firm. He will oversee fixed-income portfolio management while continuing his chief economist role. Mueller says he has worked at Strong for 11 years.