Nationwide has reported a sharp fall in mortgage lending, mainly due to making fewer buy-to-let loans.
Net mortgage lending fell to £2.4bn in the April-to-June quarter, down from £3.5bn a year earlier.
The building society also said more people opened a current account with it during the three-month period than with any other provider.
Nationwide's profits for the quarter fell 20% to £322m, after last year's results were helped by a one-off gain.
A year earlier, the building society had received a £100m boost to its profits from the sale of its investment in Visa Europe.
Announcing the latest results, chief executive Joe Garner said "Profit performance in the first quarter remained comfortably within our strategic target range and, after allowing for one-off items, was broadly consistent with the prior period."
Nationwide had a 13% share of the mortgage market in the quarter, down from 15% in the same time last year.
A spokesman for the building society said it expected its buy-to-let lending to remain "broadly flat".
Nationwide had "raised the bar for landlord's affordability before most other lenders with the aim of helping ensure our borrowers can meet future repayments", he added.
"This, together with a softening of lending due to Stamp Duty and tax changes, led to a decline in buy-to-let."
In the first quarter Nationwide opened 202,000 new current accounts, a rise of 17% on the same time last year.
The company also said that more than a fifth (22.4%) of all people switching current accounts had moved to Nationwide.