Coventry Building Society set new records in 2005 as it enjoyed "one of the best ever years" in its 122-year history.
Gross lending rose by £811 million to more than £3 billion and the net lending figure, which takes account of redemptions, was also a record at £1.3 billion.
The net lending figure means that the Coventry, the country's fifth largest building society, is punching 64 per cent above its "natural" market share.
On the other side of the book, savings balances rose by £897 million - 42 per cent above weight - while assets grew by 17.5 per cent to more than £11 billion. Pretax profit rose by £2.1 million to £53.7 million after stripping out £2.9 million to cover loan impairment.
The Coventry said its management expenses ratio, as a proportion of average assets, shrank by two basis points to 0.57 per cent and was the best in the sector.
The net interest margin, the difference between the interest the Coventry charges its borrowers and the rate it pays to savers, worsened marginally to 0.96 per cent from 0.95 per cent in 2004 but was still one of the narrowest in the industry.
Last year saw the Coventry sign up more than 76,000 new members, bringing the total to more than one million.
Overall, the figures show that the society is now a regional mutual with a national reach, chief executive Martin Ritchley said.
"The mortgage and savings markets remained as competitive as ever in 2005.
"Despite this, the society achieved an unprecedented level of new lending and this was an impressive performance against the background of a more subdued housing market.
"The continued high levels of employment and comparatively low interest rate environment have sustained mortgage repayments and kept arrears levels low."
Arrears at the end of the year were less than half the industry average, Mr Ritchley added.
The society has been doing its bit to help struggling first-time buyers get on to the property ladder and has won new business through prod-ucts such as the Step Up mortgage which takes parents' income into account.
New savings products include a range of accounts for the over-60s as well as Family First, an account tailored to the new child trust funds and child benefit.
Money is being spent on upgrading the society's 49-strong branch network, which even though it is winning more and more business via the internet and the telephone is still a major part of its operations.
Mr Ritchley said although the 2005 results were "truly outstanding", he expects the Coventry to do as well this year in a still-buoyant housing market.
"Last year we saw prices rise by between zero per cent and five per cent and we should see the same again in 2006. We don't see the market roaring away but neither do we see it crashing."