It is never too late to invest in mutual funds for retirement. As such, if you plan to invest in some of the best funds, the Zacks Mutual Fund Rank can provide you with valuable guidance.

How can you tell a good mutual fund from a bad one? It's pretty basic: if the fund is diversified, has low fees, and shows strong performance, it's a keeper. Of course, there's a wide range, but using the Zacks Mutual Fund Rank, we've found three mutual funds that would be great additions to any long-term retirement investors' portfolios.

Let's break down some of the mutual funds with the top Zacks Mutual Fund Rank and the lowest fees.

Mirova Global Sustainable Equity Y (ESGYX Quick QuoteESGYX - Free Report) has a 0.95% expense ratio and 0.8% management fee. ESGYX is a Global - Equity mutual fund. These funds invest in large markets like the U.S., Europe, and Japan, and operate with very few geographical limitations. With yearly returns of 11.17% over the last five years, this fund clearly wins.

Fidelity New Millennium (FMILX Quick QuoteFMILX - Free Report) . Expense ratio: 0.61%. Management fee: 0.38%. FMILX is an All Cap Growth mutual fund. In order to increase diversification, these funds have holdings across small, medium, and large-cap levels. This fund has managed to produce a robust 10.92% over the last five years.

State Street Institutional US Equity Services (SUSSX Quick QuoteSUSSX - Free Report) is an attractive large-cap allocation. SUSSX is part of the Large Cap Blend section, and these mutual funds most often invest in firms with a market capitalization of $10 billion or more. By investing in bigger companies, these funds offer more stability, and are often well-suited for investors with a "buy and hold" mindset. SUSSX has an expense ratio of 0.65%, management fee of 0.37%, and annual returns of 12.74% over the past five years.

There you have it. If your financial advisor had you put your money into any of our top-ranked funds, then they've got you covered. If not, you may need to talk.