The Jaguars made their trade with the Lions official on Tuesday, sending WR Dennis Northcutt to Detroit in exchange for safety Gerald Alexander, the Jaguars announced.
The rare player-for-player swap appears to fill pressing needs for both teams.
Alexander, who suffered a fractured vertebra last season, passed a physical for the Jaguars on Monday, but it wasn't until Tuesday that satisfactory results came back from Northcutt's physical in Detroit.
A second-round pick in the 2007 NFL Draft, Alexander is expected to bolster a relatively thin group of safeties led by starters Reggie Nelson and Sean Considine. In fact, Alexander could become a bargain for the Jaguars.