Landlords trade their properties only every 17 years, compared with 14 years for the average home owner.
The finding is by Countrywide, which says that landlords are holding properties for longer than before the last recession.
Landlords now hang on to properties for five more years than they did in 2007.
However, the average time has fallen from a retention rate of 20 years in 2011.
In that same year, home owners would on average sell every 16 years.
Despite the average times, nearly 50% of private owner-occupier homes in the UK have not sold for 20 years, and almost one third of landlord-owned properties have not been sold in that time.
The Countrywide research also breaks down rents between those for new lets, rents for occupied units and rents for renewals.
Interestingly, rents on renewals are lower than both new and occupied rents.
A newly agreed rent averaged £1,287 per month in Greater London, but a renewed rent averaged £1,150 – slightly less than the average rent for an occupied unit at £1,176.
There were marked annual increases in new rent in every part of England and Wales.