Investing in mutual funds for retirement is never too late. And the Zacks Mutual Fund Rank can be an excellent tool for investors looking to invest in the best funds.

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 investors' portfolios.

Let's learn about some of Zacks' highest ranked mutual funds with low fees you may want to consider.

Fidelity Focused Stock Fund (FTQGX) has a 0.79% expense ratio and 0.68% management fee. FTQGX is a Large Cap Growth option; these mutual funds purchase stakes in numerous large U.S. companies that are expected to develop and grow at a faster rate than other large-cap stocks. With yearly returns of 14.23% over the last five years, this fund clearly wins.

American Funds Investor Company of America F1 (AICFX Quick QuoteAICFX - Free Report) : 0.63% expense ratio and 0.23% management fee. AICFX 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. With yearly returns of 14.3% over the last five years, AICFX is an effectively diversified fund with a long reputation of solidly positive performance.

Goldman Sachs SmCap Eq Insights R6 (GCSUX). Expense ratio: 0.83%. Management fee: 0.8%. Five year annual return: 10.1%. GCSUX is a Small Cap Blend mutual fund, allowing investors a way to diversify their funds among various types of small-cap stocks.

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.