Revolut, the London-based digital banking start-up, has raised $800m in a funding round that makes it the UK’s most valuable private tech company of all time.

The deal, led by SoftBank’s Vision Fund 2 and Tiger Global Management, values the six-year-old company at $33bn (£23.9bn), six times more than at its last fundraising in early 2020. The company is now worth more than NatWest, one of the UK’s Big Four retail banks.

The rapid increase highlights insatiable demand from investors for fast-growing companies, which has renewed concerns about overheating in private tech markets. Investors poured almost as much money into private start-ups in the first half of this year as they did in the whole of 2020.

Mikko Salovaara, Revolut’s chief financial officer, said the company did not need to raise money but added that “the environment for raising is very strong and we had a lot of investor interest”, so it decided to take advantage.

Revolut said it would use the new cash to ramp up spending on marketing, particularly in the US and India, and on new product development.