This gives mutuals a 24% market share of gross lending in the first half of 2013, up from 21% in the first half of 2012.
Net new mortgage lending (gross lending minus repayments) by mutuals was £1.4bn in June and £5.5bn in the first half of the year, up from £2.6 billion in the first half of 2012.
Building societies and other mutual lenders approved a total of 165,800 mortgages in the first half of the year, up 17% compared to the 141,200 in the same period last year.
Brian Morris, head of savings policy at the BSA, said: “Building societies and other mutual lenders have performed strongly in the mortgage market during the first half of the year, with net lending of £5.5bn more than double the amount they lent in the same period last year.
“In contrast lending by other institutions, such as banks, was negative in the first half of 2013 at minus £3.0bn as mortgage repayments outstripped new lending by those institutions.”
The figures also revealed that mutuals have increased their lending across the spectrum to all types of borrowers including first-time buyers and those with small deposits.
Lending to first-time buyers accounted for almost a third of all lending by the sector in the year to June, helping 38,000 people take the first step on to the property ladder.
