After just over three years at the company, Mentel has departed because he has achieved his goal, according to a statement from the company.
His task was to "pull together a team of fund managers who could build a credible multi-manager business and establish Octopus in a market outside its traditional tax-efficient products," the statement read.
The company now has over half its £2.3bn AUM in multi-manager investments, it continued.
Guy Myles, the company’s managing director and founder, will take on direct responsibility for the multi-manager team in what he termed a "simplification" of the business.
"We positively want to structure it in this way. This is not something where we feel forced to act. It’s a tough and difficult thing to do, but also something we have thought long and hard about and which is in the long-term interests of the company," he added.
The company’s statement said it would like to take this opportunity to thank Mentel for all his hard work.
Now the fund range is sufficiently focused and the teams sufficiently integrated, it is felt the individual fund managers can collectively drive forward the Octopus investment philosophy, it said.
Day-to-day management of the funds will be unaffected and continue to fall under the auspices of fund managers Bish Limbu and Colin Lunnon, as well as the broader multi-manager team.
Myles will be responsible for continuing to grow the multi-manager business and for managing key client relationships.