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.

The easiest, most reliable way to judge a mutual fund's quality over time is by analyzing its performance, diversification, and fees. The Zacks Mutual Fund Rank, which covers over 19,000 mutual funds, has helped us identify three outstanding options that are perfect for any long-term investors' portfolios that is retirement-focused.

Here are the funds that have achieved the Zacks Mutual Fund Rank #1 (Strong Buy) and have low fees.

Fidelity Advisor Biotechnology I

(FBTIX) has a 0.73% expense ratio and 0.53% management fee. FBTIX is classified as a Sector - Health fund. Healthcare is one of the biggest sectors of the American economy, and these kinds of mutual funds provide a great opportunity to invest in this industry. With yearly returns of 12.58% over the last five years, this fund clearly wins.

Voya Mid Cap Opportunities Portfolio Adviser

(IAMOX): 1.16% expense ratio and 0.79% management fee. IAMOX is a Mid Cap Growth mutual fund. Mid Cap Growth funds pick stocks--usually companies with a market cap between $2 billion and $10 billion--that demonstrate extensive growth opportunities for investors compared to their peers. With yearly returns of 9.24% over the last five years, IAMOX is an effectively diversified fund with a long reputation of solidly positive performance.

JPMorgan Intrepid Value Fund R6

(JIVMX). Expense ratio: 0.34%. Management fee: 0.3%. Five year annual return: 11.27%. JIVMX is a part of the Large Cap Value category, and invests in equities with a market capitalization of $10 billion or more, but whose share prices do not reflect their intrinsic value.

We hope that your investment advisor (if you use one) has you invested in one or all of the top-ranked mutual funds we've reviewed. But if that isn't the case, it might be time to have a conversation or reconsider this vitally important relationship.

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