M&G, which recently demerged from insurer Prudential, said the M&G Recovery Fund will adopt a refreshed investment approach with an increased focus on "unloved, mid-sized companies".
Michael Stiasny will succeed Dobell as manager of the fund when he leaves the firm at end-December, M&G said.
Dobell joined M&G in 1992 as a UK equity manager on the segregated pension fund desk. The Recovery Fund has delivered a 127.7% cumulative post-fees return since 2000, compared to a return of 118.4% in the FTSE All Share index.
(Reporting By Sinead Cruise, Editing by Abhinav Ramnarayan)