Williams de Broe chief executive Philip Howell has resigned and has been replaced by Investec Wealth & Investment chief executive Jonathan Wragg.
The integration of Investec Wealth & Investment with Williams de Broe is expected to conclude next March.
Howell has stepped down with immediate effect and Wragg will take the position of chief executive of the combined business in September.
Howell joined Williams de Broe in February 2010 and oversaw the acquisition of parent Evolution Group by Investec in September.
Williams de Broe chief operating officer David Howard is also set to leave but will depart at the end of the year. Investec Wealth & Investment COO Judy Price will take on the role across the combined group in September.
In April, Investec Wealth & Investment confirmed it would drop the Williams de Broe name and the wealth manager would be merged into its parent.