Timothy Parton, a manager on top performing JPMorgan American (JAM ), has entered his final month on the investment trust, following a particularly strong year.

Parton has run the growth side of the £1.7bn portfolio since 2019 when it announced a switch in strategy which saw two growth and value-style fund managers to run its mostly large company portfolio.

Following a long-established succession plan, Parton will leave the growth part of the £1.7bn portfolio in the hands of Felise Agranoff, who was appointed in 2022, after the board of JAM initially announced Parton’s planned departure.

Agranoff has been with JP Morgan Asset Management for 20 years, starting out as a research associate in 2004.

Jonathan Simon, who has run the value part of the portfolio since 2019, remains in post.

JAM chair Kevin Carter thanked Parton for assisting in the delivery of ‘impressive returns for shareholders, successfully navigating the challenging market conditions of the last few years’.

‘Tim leaves the company’s large-cap portfolio in very safe hands, with Felise and Jonathan a proven team in pursuing their complementary growth and value investment approach to US equities,’ Carter said.

The revamped managerial strategy has proved successful and JAM produced strong results in 2023 with total underlying returns of 27.7% and a 26.6% rise in the share price, compared to the S&P 500’s 18.9% jump.

Over three years JAM is the top-performing US equity trust by a long way, with its shares gaining 50.8% and its underlying value rising 57.7%, compared to the sector’s average share price rise of 41% and net asset value returns of 42% respectively.