Originally, this was more of a conceptual question that I tried to Google, but after looking through many sources, I keep seeing different definitions and terminologies and a combination of them that I lost track of their actual meanings, and which are referring to the same things:

  1. mutual fund
  2. index fund
  3. mutual ETF
  4. index ETF
  5. index mutual fund
  6. index mutual ETF
  7. ETF

Someone told me that DIA is an index ETF that indexes DJI, which makes sense, but all the other terminologies are really tripping me right now. Another source told me that ETFs and mutual funds can be index funds, but they don’t have to be, what's an example of that? And then other sources say that an ETF is a specific type of mutual fund. In any case, I just don't see the big picture with all these technical semantics.


2 Answers 2


Mutual funds and exchange-traded funds (ETFs) are, as the names suggest, types of funds. (You can read about the differences between them here.) However, funds can also be index funds or actively managed funds. Though some are more common than others, you can have all 4 combinations. So for example, a mutual fund could either be an index fund or actively managed. And an index fund could either be a mutual fund or an ETF. The only things in your list that don't make sense are the ones that combine mutual fund and ETF, so #3 and #6.

For specific examples, VFIAX is a Vanguard mutual fund that tracks the S&P 500. Then there is VOO, which is a Vanguard ETF that also tracks the S&P 500. So both would also be called index funds. By contrast, something like FCNTX (Fidelity Contrafund) is an actively managed mutual fund that seeks to outperform the S&P 500. There are actively managed ETFs as well, but they aren't particularly common as of now.

  • a mutual fund can be an index fund and an index fund can be an etf... does that mean a mutual fund can be an etf?
    – Pvo
    Commented Apr 28, 2020 at 3:44
  • So, what going back to what Ben said "Exchange-traded funds (ETF) are special types of mutual funds that are traded on the stock exchange like a stock." Is that why I cannot buy VFIAX through my brokerage but VOO can be traded?
    – Pvo
    Commented Apr 28, 2020 at 3:47
  • @Pvo It's really just a semantics issue but in general I would not say that an ETF is a type of mutual fund or vice versa. A square can be blue and a circle can be blue but that doesn't mean a square can be a circle or vice versa. You can't buy VFIAX through your (presumably non-Vanguard) brokerage because you have to buy it directly from Vanguard, which your brokerage has no interest in facilitating (unless you're willing to pay steep transaction fees), whereas VOO you can buy on an exchange from anybody that's selling it.
    – Craig W
    Commented Apr 28, 2020 at 11:41
  • @Pvo To confuse things further, Vanguard's ETFs often are a special class of their mutual fund. But they have a patent on this structure so I believe they are the only brokerage that can do this currently.
    – Craig W
    Commented Apr 28, 2020 at 11:48

First, let's define a mutual fund. When you invest in a mutual fund, the fund itself is invested in multiple investments. The mutual fund allows you to make diversified investments in an easy way. For more information, see What is a mutual fund?

Now that we know what a mutual fund is, let's talk about stock mutual funds. Mutual funds can invest in any number of different investments (bonds, precious metals, short-term debt), but stock mutual funds are mutual funds that invest primarily in stocks. Stocks are probably the most common investment for mutual funds, so often when you hear about mutual funds, it is assumed that it is investing in stocks.

The managers of a fund decide what specific investments a mutual fund will make. Mutual fund management can be split into two broad categories: Actively-managed and passively-managed. In an actively managed fund, the managers take an active role in researching potential stocks and continuously making buy and sell decisions for the fund. In a passively-managed fund, the fund invests in a fixed list of stocks, and rarely buys or sells new stocks. Passively-managed funds have several advantages over actively-managed funds, including lower fees and less stock turnover, resulting in tax advantages. The list of stocks that passively-managed funds invest in is usually the same as a stock index or group of indexes, so another name for passively-managed funds is index funds.

Exchange-traded funds (ETF) are special types of mutual funds that are traded on the stock exchange like a stock. With traditional mutual funds, you generally send your investment money directly to the mutual fund manager, but with an ETF you invest in the fund by buying shares of the ETF from your stock broker in the same way that you would purchase shares of an individual stock. ETFs can be either actively-managed or passively-managed (index funds), but the majority of ETFs are stock index mutual funds, so sometimes you will see people discuss ETFs and assume that they are index funds. For more information, see What are the important differences between mutual funds and Exchange Traded Funds (ETFs)?

  • What about an index ETF? Would DIA be an example of that?
    – Pvo
    Commented Apr 28, 2020 at 3:51
  • @Pvo As I said in my answer, most ETFs are index funds. Yes, DIA is an ETF that tracks the Dow Jones Industrial Average (a stock index). It is an index ETF.
    – Ben Miller
    Commented Apr 28, 2020 at 4:00

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .