Private healthcare giant Bupa is understood to have agreed a 100,000 sq ft deal with Peel Group for a new office in Salford Quays.
Bupa is believed to be looking at vacant sites near to its current Anchorage base in Salford Quays as the location for the build-to-suit office.
Bupa occupies 130,000 sq ft across Peel's Anchorage and Victoria buildings, where its leases are due to expire later this year.
Bupa launched a 140,000 sq ft requirement in 2011, and by 2012 had shortlisted a block in Peel Media's MediaCityUK phase two, alongside Ask Development's First Street, Allied London's Spinningfields and Co-operative Group's Noma in Manchester as potential locations.
However in 2013 the requirement was believed to have been shelved.
Bupa is represented by Cushman & Wakefield.
A Bupa spokesman said: "We have spoken to our people about our plans to move to a new base in Salford Quays. Final decisions are still being made so we can't comment further at this stage."
Peel Group declined to comment.