Paul Stephany has stepped down as manager of the £1bn Newton UK Equity fund, which he has managed since September 2014.
Mr Stephany, who remains with the fund house, will also step aside from the UK Opportunities fund.
Christopher Metcalfe will take over management of both funds for an unspecified period of time.
Mr Stephany began managing the UK Opportunities fund in February 2013.
Newton’s parent company BNY Mellon Investment Management said: “It is not our policy to comment on any individual employees.
“However, we can confirm that Paul Stephany is not currently performing any fund management roles. Christopher Metcalfe is managing the Newton UK Opportunities fund and the Newton UK equity fund in the interim.”
Mr Metcalfe, who also currently manages the Newton UK Income fund and Multi-Asset Growth fund, had previously managed the UK Equity fund between 2007 and 2011 before he moved to the multi-asset team.
Newton UK Equity fund returned 1.4 per cent over one year, compared with the UK All Companies sector, which lost 8.6 per cent over one year, according to FE Analytics.
Darius McDermott, managing director of Chelsea Financial Services, said: “There appears to have been a lot of change at the UK desk of Newton in the past four years.
“Normally this is a sign of poor performance, but actually when looking at the figures this doesn’t seem to be the case at all.
“Chris is known to us and is a very good manager, however, we would like to see the UK team settle down.”