Nationwide has increased its share of net mortgage lending to 15.7 per cent, well above its expected market share of 7.9 per cent.
Commercial and treasury director Stuart Bernau says Nationwide wrote the same amount of mortgage business in the first half of 2003 as it did in the whole of 2002.
Its interim results show its gross market share stands at 9 per cent, a 1 per cent increase from the Council of Mortgage Lenders' figure of 8 per cent in July.
Bernau says the increase is a result of lenders such as Barclays losing some of their market share. He also believes HBOS could find it hard to maintain its 26 per cent market share.
Nationwide's profits were £188.4m in the six months to October from £154.2m last year while total assets grew by 9.9 per cent to £93.9bn from £85.4bn in April.
Bernau says: “We are not the sort of organisation to grow through mergers or takeovers. All of our growth is coming from business joining us because of our pricing policy.
“We are retaining far more of our customer base than many of our competitors, many of whom lose the same amount of business that they write.”