The product transfer data previously reported by UK Finance was inflated by £14.9bn and £17.8bn due to a reporting error from one of its members.
The trade body revised down its product transfer data in the first two quarters of the year at the same time as releasing Q3 data.
Following the revision there was £38.8bn of product transfer business in Q1 and £36bn in Q2, as well as £38.7bn in Q3.
Previously it was reported that there was £53.7bn (down £17.8bn) of product transfers in the first quarter and £53.8bn (down £14.9bn) in the second.
A UK Finance spokesperson said: “Product transfers is a new data set which UK Finance has reported on from beginning of 2018.
“This latest release for Q3 2018 includes material revisions to the historic data we published previously for Q1 and Q2, due to member data resubmissions, made following the identification of a reporting error which has now been rectified.
“Despite the downwards revisions, these figures show that customer engagement remains high and the majority of mortgage customers switch to a new deal shortly after their previous deal expires.”
The change means previous conclusions that the product transfer market is worth £200bn of the year are likely to be wide of the mark.
Based on the revised figures it’s more lilely to be in the region of £150bn.
A UK Finance representative admitted there has been teething issues in reporting the data, which was first reported in July.