Fidelity is merging the £449m Fidelity MoneyBuilder Growth fund into the £85m Fidelity UK Opportunities fund.
The firm said the two funds - both run by Leigh Himsworth - "share many investments in common" and investors may find it difficult to decide which to invest in.
The merger is due to take place on 24 June, subject to shareholder approval.
"Both funds have relatively concentrated portfolios of around 40 UK-listed companies and have the same reference index in the FTSE All Share," a Fidelity spokesperson explained.
"The two funds also have a similar risk-return profile that may make it difficult for new investors to identify which fund may be most suitable for them.
"Merging them will simplify our fund range and will see a reduction in the ongoing charges for the UK Opportunities fund, with the OCF of the W share class falling from 0.95% to 0.67%.
"Over three years the MoneyBuilder Growth fund - which launched in 1994 - has returned 20.1% against the 28.4% average return of the IA UK All Companies sector, while the UK Opportunities fund - which sits in the same sector - has returned 17.3% over the same period, FE data shows.