The Cubs designated Stout for assignment Thursday.
Stout will cede his spot on the 40-man roster and 26-man active roster to right-hander Adrian Sampson, whose contract was selected from Triple-A Iowa. His demotion comes after he was one of the few bright spots for the Cubs in Wednesday's 19-5 loss to the Padres. Stout worked 1.2 perfect frames in long relief, striking out four of the five batters he faced.