Societies approved 189,000 mortgages totalling £26.4bn over the period compared to £96.8bn for the market as a whole.
Net lending was £6.5bn during this period, accounting for a 57% share of the market.
Paul Broadhead, head of mortgage policy at the BSA, said: “This data again demonstrates the key contribution that building societies’ are making to the UK mortgage market.
“Mortgage approvals are up, mortgages balances remain steady and building societies accounted for over half of net lending in the first half of the year, against a natural market share of 20%.
“Whilst our support to first-time buyers and aspiring home owners remains strong, the building society sector continues to service the whole spectrum of borrowers, including people requiring a mortgage that lasts into retirement.
“The sector continues to provide innovative products helping to encourage diversity and ensure a wide range of borrowers’ needs are served.”
In terms of mortgage balances building societies currently have a 29% market share of £257.7bn compared to £1.267.7 trillion for the whole market.
