The firm said Mr Sexton, who has a 30-year track record working in investment markets, had “decided to leave the firm to take some time out and consider the next chapter of his life.”
Andrew Birt, who has been with the company for 16 years and has worked alongside Mr Sexton as head of research, has continued to oversee the investment research function since Mr Sexton’s recent departure.
The firm, which is part of James Hay parent company IFG, says Mr Birt is supported by a team of investment analysts and investment decisions “continue to be challenged and overseen by the investment committee, which comprises both internal and external investment experts.”
Saunderson House insisted the changes had not impacted the day-to-day management of clients’ portfolios.
A spokesman added: “Our well-developed succession plan means that Andrew and the rest of the team have been able to seamlessly continue to deliver our award-winning investment proposition.”
Tony Overy, chief executive at Saunderson House, said: “I would like to thank Chris for his hard work and his contribution to the success of Saunderson House over the last 14 years.
“Chris has played an important role in embedding our award-winning investment process within the firm and building the investment team.
“I wish him the very best for the future.”
Mr Sexton said: “After almost 30 years living and breathing economics and investment markets, I have come to the difficult decision that now is the right time to hand on the baton.
“The investment research team at Saunderson House is exceptional.
“I have no doubt that they will rise to the challenge and maintain our reputation for outstanding investment performance.
“I wish my colleagues and our clients the very best and look forward to hearing about Saunderson House’s continued success.”