A statement provided by a spokeswoman said Mr. Gartside has decided to leave the firm to pursue other opportunities. Further details could not immediately be learned.
Iain Stealey, portfolio manager, will take over Mr. Gartside's role. Mr. Stealey also will continue to co-manage strategies that Mr. Gartside ran alongside Robert Michele, chief investment officer and head of global fixed income.
The statement said there will be no changes to the investment processes.
Mr. Gartside joined JPMAM in 2010.