De Jong cleared waivers and was outrighted to Triple-A Indianapolis on Monday.
The Pirates designated De Jong for assignment Friday.
The Pirates selected De Jong's contract from Triple-A Indianapolis on Sunday.
The Pirates designated De Jong for assignment on Tuesday, Jason Mackey of the Pittsburgh Post-Gazette reports.
De Jong was activated from the 15-day injured list by the Pirates on Friday.
De Jong (back) is scheduled to begin a rehab assignment Tuesday with Triple-A Indianapolis, Justice delos Santos of MLB.com reports.
De Jong (back) will throw live batting practice this weekend, Jason Mackey of the Pittsburgh Post-Gazette reports.
De Jong has been diagnosed with a lumbar spine muscle strain, Kevin Gorman of TribLive.com reports.
De Jong (undisclosed) was placed on the 15-day injured list Friday, retroactive to April 13.
De Jong allowed three earned runs on four hits to blow the save Wednesday against the Reds.