The emergence of prominent activist investor Edward Bramson as a shareholder in Barclays will add to the pressure on chief executive Jes Staley and the group's underperforming investment bank, analysts have warned.

Bramson's Sherborne Investors on Monday revealed it had acquired 5.2% of the voting rights in Barclays — a move that came less than a month after the UK banking group reported a near £2bn loss for 2017.