Allianz Global Investors has created a 17-person global growth team led by CIO Thorsten Winkelmann, combing its global equity and European growth expertise - with the restructure resulting in Lucy Macdonald leaving the business.
Winkelmann and his deputy Christian Schneider have more than 40 years' investment experience and will manage some £21bn in assets in the combined operation.
Macdonald, who headed up the global equity team since 2001, is to leave the business after 19 years. She was portfolio manager of the Brunner investment trust.
An announcement to the stock exchange confirmed her departure from the company.
It said: "Matthew Tillett, who has worked closely with Macdonald on Brunner for a number of years, will lead the management of the portfolio supported by global equity managers Jeremy Kent, a long-standing member of her team, and Marcus Morris-Eyton, a long-standing member of the European Growth team of Allianz GI, the company's investment manager."
Company chairman Carolan Dobson added: "We would like to thank Lucy for the huge contribution that she has made to help us get the company to where we are now.
"The Brunner investment trust is in a good place. The discount has narrowed significantly over the last few years and we have steadily increased the proportion of our shares held by wealth managers and platforms which now stands at around 40%."
Paul Schofield, currently Macdonald's deputy within Allianz GI, will take the lead portfolio manager role for its global high alpha strategies.
A spokesman said: "As part of this pooling of capabilities, Allianz GI remains fully committed to enhancing further our already strong, wider European equity growth franchise."