Ferentz announced his retirement from the NFL on Monday, Doug Kyed of the Boston Herald reports.
Ferentz is re-signing with the Patriots, Mike Reiss of ESPN.com reports.
Ferentz was activated from the reserve/COVID-19 list Wednesday, Phil Perry of NBC Sports Boston reports.
The Patriots placed Ferentz on the reserve/COVID-19 list Friday, per the NFL's official transactions log.
Ferentz signed a contract with the Patriots on Thursday.
Ferentz was waived by the Broncos on Tuesday, The Denver Post reports.
Ferentz signed his one-year free-agent tender with Denver on Monday, Nick Jhabvala of The Denver Post reports.
Ferentz (knee) returned to practice Tuesday.