Platform, the intermediary lender of the Co-operative Bank, has stopped lending to portfolio landlords.
The organisation will only lend to landlords with three or fewer buy-to-let properties and said in a statement this decision follows the Prudential Regulation Authority's supervisory statement on underwriting standards for portfolio landlords.
In this statement, released a year ago, the regulator said lending to portfolio landlords - defined by the PRA as being those with four or more mortgaged buy-to-let properties - should be assessed using a specialist underwriting process.
It set an implementation timeline of 1 January 2017 for the more straightforward changes in the statement, and 30 September 2017 for the remainder.
Platform said any applications received through The Co-operative Bank, Britannia or Platform brands before the 25th August 2017 will be honoured.
Christopher Taylor, from the London Mortgage Brokers Limited, said it was harder for portfolio landlords to find mortgages but he added that Platform’s share of the buy-to-let market had already dropped.
“I don’t anticipate this making a huge difference,” he said. “The Co-op tends to be more driven by residential rates, and there Platform is very competitive."