Duffey has exercised the opt-out clause in his minor-league contract with the Cubs and will need to either be released or added to Chicago's 26-man active roster in the next 48 hours, Robert Murray of FanSided.com reports.
The veteran reliever has put up a 4.43 ERA with 24 strikeouts across 18 appearances with Triple-A Iowa. Unless the Cubs are willing to clear a spot for him in the big-league bullpen, Duffey should head to the open market by the end of the weekend.