The leaders of AllianceBernstein have picked a longtime McKinsey & Co. executive to take the helm of its global client group — which includes teams focused on sales, product development and marketing — in a few weeks.

Onur Erzan will join AB as head of its global client group, which has a presence on four continents, on Jan. 4. He will take the seat of Bob Keith, who has been with AB for more than 24 years, and will report to President and CEO Seth Bernstein.