Morningstar has lost some faith in the Newton Multi Asset fund since Matthew Brown has taken over the day to day management of the fund.
The rating agency has downgraded the £2.8bn fund from silver to bronze.
Iain Stewart had been running the fund since January 2005. He was joined by Matthew Brown in February 2013, who took on the position of co-manager. Since that time, Mr Brown has taken on the day-to-day management of the fund, while Mr Stewart manages the macro position.
In light of this, Morningstar’s thoughts on the fund have “waned”.
Mr Stewart is in charge of the group’s £9.8bn Real Return fund.
In the past five years, the fund has underperformed the peer group average, returning 36.5 per cent, compared to IA Mixed Investment 40%-85% Shares sector, which had returned 46.3 per cent in the same period, according to the January factsheet.
Newton did not respond to requests for comment in time for publication.