Mackey will be joining Freddie Mac the week of Nov. 11 from his most recent position as executive vice president and chief financial officer of Ally Financial.
As CFO, he led a team of 1,000 finance staff with responsibility for the oversight of the company's financial analysis, controls and reporting, accounting, business planning and investor relations.
Upon Mackey's arrival, current Freddie Mac executive vice president and CFO Ross Kari will proceed with his previously announced plans to retire from the company.
Prior to joining Ally in 2009, Mackey served as CFO for the corporate investments, corporate treasury and private equity divisions at Bank of America.
Earlier in his tenure at Bank of America, he held a variety of roles within the company, including serving as managing director within the Global Structured Products Group.