The gap between how much it costs mortgage lenders to borrow from the wholesale market and how much they charge consumers is at its biggest ever, with homebuyers getting the raw end of the deal.
While mortgage rates for consumers have fallen since the base rate tumbled to its all-time low of 0.5 per cent, they have not fallen fast enough to keep up with the fall in swap rates, bringing the margin to a record high.
For example, the average two year fixed rate mortgage costs the mortgage lender 1.26 per cent in swap rates, and costs the borrower 4.55 per cent, a margin of 3.29 per cent.
In comparison, this margin between what a two year fixed rate mortgage cost lenders and borrowers two years ago was just 1.28 per cent.
The average three year fixed rate has an even larger margin of 3.57 per cent between the rate paid by the lender and that paid by home owners.
Commenting on the record profit margin for lenders, Michelle Slade, spokesperson for Moneyfacts.co.uk, said: "Borrowers will be angered that they continue to pay the price for mistakes made by lenders, particularly those who have accepted government funding."
While availability is improving, and the highest loan to value is rising, Ms Slade still finds the mortgage market to be far from a state of "normality".
"Swap rates are the traditional barometer of fixed rate mortgages, but with lenders still nervous of entering the money markets many are opting for on balance sheet funding through their savings book.
"While the margin between fixed rate savings and mortgages is lower, it is steadily increasing again."
The base rate might have fallen far, but the mortgage rates on offer are not so different to what borrowers would have expected to pay when it was higher, Ms Slade said.
"Borrowers could see interest rates as high as 8% if bank base rate rises as quickly as it fell and lenders retain these record high margins."
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