Coventry Building Society grew its mortgage assets by £3bn last year, according to its results for 2017.
This growth of 9 per cent meant it was nearly 3 times faster than the rest of the market as a whole.
Mark Parsons, chief executive at Coventry Building Society, said its success was due to its close relationship with intermediaries.
He said: "2017 was another strong year for the society, with our mortgage assets growing by nearly three times the market. Just as importantly we’ve grown in the right way, focusing on the needs of intermediaries and their clients.
"We have delivered on our promise to recognise the work intermediaries do by introducing procuration fees for product transfers, and the developments we’ve made to our buy to-let proposition have consolidated our position as a leading lender in this sector.
"The mortgage market is very competitive and we will work hard to maintain our performance as client and broker expectations rise. We are investing in our intermediary partnerships and the services we provide to do exactly that."
Overall mortgage assets increased to a record £35.9bn. This is the 11th year in a row Coventry Building Society has outgrown the mortgage market, with this growth supported by an 11 per cent increase in savings balances.
Profits increased by 2 per cent to £243m as the society consolidated its strong capital position.
The society's cost to mean asset ratio was 0.42 per cent, the lowest reported by any building society, while mortgage arrears fell and were only a sixth of the industry average.
