Nucleus wrap operations director Jeff Spence is to depart after more than five years with the firm to join Alliance Trust Savings.
Spence will become operations director at ATS, working to combine the Stocktrade business which it acquired in May with the ATS platform.
ATS estimates the Stocktrade deal could add as much as £4.6bn in new assets to its business, created a combined unit of more than £11.5bn.
Spence replaces Elaine Maddison, who was appointed strategy director earlier this year. He will also join the ATS executive team.
ATS managing director Patrick Mill says: “Jeff will be responsible for the operations of the business and will play a major role in the continued growth of ATS in the platform market. Jeff’s wealth of experience in the platform market will help us drive the company forward.
“Jeff will work with the team to focus on our aim of driving growth organically and profitably through the three main channels.”