Vanguard, the low-cost US asset manager, has added a self-invested personal pension to its fast-growing UK retail platform — a move that is likely to pile pressure on larger rivals to lower fees.

The $5.6tn Pennsylvania-headquartered firm launched its direct-to-consumer platform in the UK in 2017, and has amassed 85,000 clients and £2.5bn in assets. This has grown from 50,000 customers and £1.4bn in assets in June 2019.