The deal will include the sharing of “knowledge and expertise”, according to Nationwide, but will not include the sharing of customer data by either party.
Bunk uses technology, including open banking, to help improve the rental market for both landlords and renters, the building society said.
The investment is the latest deal from the £50m venturing fund set up just over a year ago to create partnerships enabling the society and start-ups to share common goals.
As part of the fund, Nationwide has made strategic investments in and partnering with early stage start-ups exploring “innovative products and services” that could provide real benefits for the society’s members.
Bunk has already partnered with Experian so tenants who make regular rent payments on time will see this reflected in their credit file. Nationwide said this was something which started to redress the balance between renters and homeowners.
And Bunk also offers support and advice for those who have become accidental landlords.
Reduced margins and more regulation
Tom Woollard, CEO of Bunk, said: “Landlords are facing reduced margins coupled with increased regulation and there has never been a better time to make their lives easier through the use of technology.
“Bunk is there to make the process less stressful and more enjoyable for both renters and landlords. Bunk’s mission is to make renting work for everyone and we’re thrilled to have a partner like Nationwide backing our vision.”
Bunk automatically lists a landlord’s property on relevant sites and verify tenants as well as by verifying the landlord proof of ownership.
Once properties are listed, landlords can view them on a dashboard, which also notifies them when a deposit and rent has been paid, saving the need to review their current account statements.
Bunk also allows tenants and landlords to correspond within the site, so enquiries such as expressing an interest in renting a property and maintenance requests will go directly to them. The site also has safeguards for renters, not allowing landlords to take more than a five week rent as a deposit.
Tony Prestedge, deputy CEO at Nationwide Building Society, said: “Nationwide is one of the biggest buy-to-let lenders in the UK and we have long campaigned to improve standards within the rental sector for both tenants and landlords.
“Bunk is combining the latest digital technology backed up with human service to not only offer a seamless digital experience but also reduce friction in the rental market between tenants and landlords.
“They are a natural fit for our venturing fund investment, which seeks to fund start-ups that are focussed on making people’s lives easier through smart insights and fair practice.”
Financial details of the transaction were not disclosed.