Dear Liz: I recently sold my home and want to put away funds for my daughters. I want to place $130,000 each in an account that will earn 7% to 10% interest for 30 years or so, providing them with a comfortable retirement fund. I’m thinking of having them start with a low-cost index mutual fund. What are the drawbacks to placing all of the funds in one mutual fund account?

What are the tax implications?

Answer: Stock market index funds mimic a benchmark, such as the Standard & Poor’s 500. That means you’re typically getting at least some diversification, which can help reduce the volatility of your investment.

You could reduce volatility even more by including bond market index funds, or opting for a target date fund that spreads the money across a mix of investments — stocks, bonds, cash. Target date funds are labeled with a specific year in the future and gradually reduce risk as that date approaches. Or you could consider a robo-advisor, which uses computer algorithms and ultra-low-cost exchange-traded funds to create and manage a portfolio.

These investments typically will generate taxable returns, so you’ll want to discuss the implications with a tax pro.

Also, you mentioned earning interest, but interest is what is paid on bonds and savings accounts. Returns are what investors earn on stocks and other higher-risk investments. No investment currently pays 7% to 10% interest. Over time, stocks typically generate average annual returns of 8% or so, but returns aren’t guaranteed and some years your stocks may lose money.