Nationwide boosted its gross lending by 44% in the 12 months to April 4 2012 to reach £18.4bn, up from £12.8bn in the same period in 2011.
It helped over 24,000 first-time buyers during the year – a 9% increase on the previous year.
The number of group residential mortgage accounts more than three months in arrears was also slightly down at 0.73%, compared with 0.77% in 2011.
But the lender admitted its base mortgage rate pledge has cost it £750m so far, with each customer benefiting by around £1,000.
A number of its borrowers have reverted to a rate capped at 2% above the Bank of England 0.5% base rate, which means there is little incentive for them to remortgage elsewhere.
During the year the lender increased its buy-to-let lending to £4.4bn, up from £3bn in the previous year. Overall, Nationwide’s underlying profits rose by 10% to £304m in the year.
Its results were hit by a £103m charge for complaints relating to the mis-selling of payment protection insurance. It has seen complaints about PPI quadruple in the past six months.
Graham Beale, chief executive of Nationwide, says the society continues to position itself as a challenger brand to the established banks.
He says: “We have bucked market trends by increasing our gross lending by 44% to £18.4bn, demonstrating our commitment to supporting growth in the economy as well as meeting the needs of borrowers – especially first-time buyers.”