The increase in lending takes its market share from 12.2% in H1 2014 to 13.2% in the six months to September this year.
Net lending also rose 14% to £4.1bn to give it a net lending market share of 21.2%.
The mutual advanced 25,700 mortgages to first-time buyers, 8% more than the same period in 2014. It plans to launch a mortgage product to support the government’s Help to Buy ISA initiative when it comes into effect on 1 December.
Buy-to-let gross mortgages accounted for £2.9bn of its total lending, up 32% on last year taking its market share in buy to let to 14.9%. In his review of the results, chief executive Graham Beale said it was too early to measure the impact of the recent tax changes and a rise in interests on the demand for buy-to-let mortgages.
Beale said competition in the lending markets remained robust and because of this Nationwide expected to see downward pressures on margins in the second half of the year and into 2016 and 2017.
Earlier this week, Nationwide announced that Joe Garner, former deputy chief executive of HSBC and currently chief executive of BT Openreach would replace Beale as head of Nationwide in the spring next year.
