It was probably with great trepidation that the board of listed buyout fund Electra Private Equity received the news that activist investment firm Sherborne Investors had taken a 10% stake.

Sherborne targets undervalued or underperforming companies with the aim of taking a sizable stake and turning their fortunes around. The firm, which is led by the American Ed Bramson, is best known for enforcing sweeping changes at asset manager F&C in 2011, and paid roughly £90 million for a 10.24% stake in Electra PE on Friday, building up to 13.7% by Tuesday.