Ferrell (biceps) was placed on waivers by the Marlins on Friday, Jake Kaplan of The Athletic reports.
Ferrell hasn't pitched all season due to biceps tendinitis. A Rule 5 pick from the Astros over the offseason, Ferrell will be offered back to Houston if he passes through waivers unclaimed. If he does get claimed, his new team will have to keep him on the big-league roster and active for at least 90 days or offer him back to the Astros.