LONDON – Startup, app-only bank Atom has passed £900 million in deposits less than two years after launching its first savings product.

Atom confirmed to Business Insider on Monday that it has attracted over £900 million in deposits since July 2016 when it first launched its savings accounts.

A spokesperson told BI: “Responsible and sustainable growth of our business has always been a priority for Atom, passing on the benefit of our low-cost model to UK consumers in the form of competitive rates.

“Our savings deposits have now grown to over £900 million, with our mortgage and business lending following a similar trajectory. We’re the fastest growing challenger bank in the UK, with cost and efficiency driving our ambition to deliver great value for customers and investors.”

The disclosure comes as Atom’s annual accounts show that the startup had £538 million in deposits from over 17,000 customers at the end of March. It means the app-only bank has attracted around £400 million in four months.

Founded in 2014, Atom is one of a number of so-called "neobanks" - startups trying to build app-only banks. Others include Monzo and Starling. Atom was founded by former Metro Bank chairman Anthony Thomson and former First Direct CEO Mark Mullen.

Thomson, Atom's chairman, writes in Atom's 2017 accounts: "Whilst there was considerable research to support our strategy, we - like many others - had no idea how quickly mobile banking would come to dominate."

The bank's accounts, filed with Companies House this week, show Atom has received over £300 million of small business loan applications and lent out close to £100 million in loans and mortgages by March this year.

Atom had a net interest loss of £1 million for the year, due to paying out interest on its 1.95% and 2.5% fixed savings accounts, at the time market-leading interest rates, before the launch of its lending products.

The bank lost £42 million last year, up from £23 million in 2015, due to "staff and operating costs as we continued to build products for launch and scaled-up teams to run a fully operational bank." Atom raised £113 million in funding during the year and ended the year with £103 million of equity capital left.

In total, Atom has raised over £200 million in equity funding from investors including Spanish banking giant BBVA and City fund manager Woodford Asset Management.