Mutual funds are a form of investment that is managed by professional experts. When you invest in mutual funds, the fund manager allocates the amount into different securities and debts, based on the plan you choose. Due to such diversification of funds and the anticipated high returns, there is a surge in mutual fund investments.

There are several funds for you to choose from. Based on your risk appetite, available funds, and the purpose of investment, you may choose funds that help meet your long-term financial goals. If you want to ensure that mutual fund is a core part of your portfolio and if your time horizon is vast, choose from one of the below-mentioned best mutual funds to invest in.

Schwab S&P 500 index
This is a large-cap fund, which is also one of the best mutual funds to invest in 2018. It generated a return of 20.5% in 2017 and has achieved a total return of 15.6% in the last five years. The annual expenses of the fund are only 0.03% of the total asset value, thus making it an ideal fund for those who are looking for a balanced return.

Vanguard mid-cap index
As the name suggests, the mutual fund invests into mid-cap stocks and had a total return of 18% in 2017. The five-year return for the fund stood at 15.2% and its annual expenses are 0.18% of the asset value.

Schwab total stock market index
This is a fund that invests in large-cap stocks. It generated a return of 19.9% in 2017 and a five-year return of 15.5%. It has an annual expense of 0.03% of its total assets.

Schwab small-cap index
Schwab small-cap index invests into small-cap securities and had generated a return of 15.1% along with a five-year return of 15%. It has an expense of 0.05% of asset value.

Fidelity international index
If you want to diversify your portfolio and include international securities in it, you should choose Fidelity International Index. It is one of the best mutual funds to invest in with regard to foreign securities. The fund generated a return of 23.5% in 2017 and a five-year return of 8.2% with annual expenses that stood at 0.16% of the company assets.

The returns keep changing depending on the market. Consider your investment purpose and long-term goals before you choose a fund to invest in. The best bets are the balanced funds that are high on return and low on risk.