The new organisation, which will be called Impetus – The Private Equity Foundation, will be led by chief executive Daniela Barone Soares, who has been chief executive of the Impetus Trust since 2006.
Shaks Ghosh, chief executive of the PEF, stepped down at the end of March.
Johannes Huth, chairman of the PEF since 2011, will chair the new organisation. Louis Elson, chair of Impetus Trust, will be vice-chair.
The new organisation, which will work from Impetus’s London offices, operates a model that combines grants, volunteer work by professional staff such as investment and management consultants, and in-depth support for charity senior management teams.
It will focus on investing in children and young people’s charities,
Before the merger the Impetus Trust had an annual turnover of about £5.9m and about 25 staff; the PEF had a turnover of about £5m a year and 13 staff. A spokeswoman for Impetus – PEF said no redundancies had been made as a result of the merger and the new organisation had 45 staff after recruiting new people.
The organisations announced their intention to merge in January.
Soares said: "At the heart of our merger is our determination to have the greatest possible impact on the lives of disadvantaged children and young people."
A statement from the organisation said that the global private equity firm Warburg Pincus had made a three-year commitment to make a "significant financial contribution" and provide pro bono volunteers to support the new charity. A spokeswoman for the charity said she could not comment on how much the financial contribution would be.