From 1987 to 1993, he held several positions in the Department of Defense, including assistant secretary for financial management and comptroller of the navy. In 1993, McCormack cofounded Trident Capital Inc., a private equity firm focusing on information and business services companies.

McCormack has been a member of the visiting committees on Chicago Booth and the Division of Physical Sciences and a member of Chicago Booth's capital campaign steering committee. He received the Defense Department's Distinguished Public Service Medal, its highest civilian honor.