Fox Sports' Jay Glazer first reported the swap.
The Panthers' defense has been littered with injuries. Rapoport reports defensive end Charles Johnson is week-to-week with a hamstring injury. Star Luke Kuechly has missed the past two games with a concussion and his return is still hazy. Carolina lost defensive end Frank Alexander in the preseason and replacement Kony Ealy hasn't shined in full-time duty.
The fit in Carolina is much better for Allen than in Chicago, where John Fox and Vic Fangio were trying to convert the long-time defensive end into an outside linebacker.
Allen currently sits as the NFL's active sacks leader with 134 and is ninth all-time in QB takedowns. The 33-year-old has shown the ability to still get after the passer in spurts this season. Most of those situations were with his hand in the dirt, not in the miss-cast linebacker duty.
With a 3-0 start to the season against teams earning a combined 2-7 record and facing the 1-2 Tampa Bay Buccaneers in Week 4, the Panthers aren't waiting around for players to get healthy. Acquiring essential pass-rushing help in Allen will go a long way in Carolina's attempts to win its third-straight NFC South title.
The Bears paid Allen's $11.5 million roster bonus this year and his base salary entering the 2015 season was only $1 million, so the Panthers are on the hook for roughly $882,000 the rest of the season.
At 0-3, the Bears are clearly in rebuilding mode -- with sights on the No. 1 overall pick. With a plethora of 4-3 defensive ends like Allen on a team switching to a 3-4 front, it made little sense to hang on to the veteran. Freeing up more time for younger players to sink or swim is the logical move for Fox and general manager Ryan Pace. In reality, it was always a surprise the Bears didn't cut Allen in March before the roster bonus became due.