I have found in in financial newsletters that it could also be translated as "gestor de activos" as in Spanish we still do not use "activista" in that sense, only as militant and similar concepts. Thanks.
Thank you for your message, and I'm sorry it's taken a while for anyone to get back to you. My Spanish is limited, but a gestor de activos would be an asset manager, is that right? I can't find any evidence that 'activist' in English has such a meaning. Can you provide any examples?