I was looking at Vanguards (VOO) ETF which aims to mimic the S&P 500 and noticed you do not pay any commission fees and it has an expanse ratio of just .05%.Then I looked at the mutual fund version of that account (VFINX) and it has an expense ratio of .17% (investor shares). Looking at these costs, i dont understand why anybody would choose to invest in the mutual fund if the expense ratio for the ETF is considerably lower and you don't pay any commission fees.

Am I missing something here?


3 Answers 3


See my comment for some discussion of why one might choose an identical fund over an ETF. As to why someone would choose the higher cost fund in this instance ...

  1. The Admiral Shares version of the fund (VFIAX) has the same expense ratio as the ETF but has a minimum investment of $10K. Some investors may want to eventually own the Admiral Shares fund but do not yet have $10K. If they begin with the Investor Shares now and then convert to Admiral later, that conversion will be a non-taxable event. If, however, they start with ETF shares now and then sell them later to buy the fund, that sale will be a taxable event.

  2. Vanguard ETFs are only commission-free to Vanguard clients using Vanguard Brokerage Services. Some investors using other brokers may face all sorts of penalties for purchasing third-party ETFs. Some retirement plan participants (either at Vanguard or another broker) may not even be allowed to purchase ETFs.


Where are you planning on buying this ETF? I'm guessing it's directly through Vanguard? If so, that's likely your first reason - the majority of brokerage accounts charge a commission per trade for ETFs (and equities) but not for mutual funds.

Another reason is that people who work in the financial industry (brokerages, mutual fund companies, etc) have to request permission for every trade before placing an order. This applies to equities and ETFs but does not apply to mutual funds. It's common for a request to be denied (if the brokerage has inside information due to other business lines they'll block trading, if a mutual fund company is trading the same security they'll block trading, etc) without an explanation. This can happen for months. For these folks it's typically easier to use mutual funds.

So, if someone can open an account with Vanguard and doesn't work in the financial industry then I agree with your premise. The Vanguard Admiral shares have a much lower expense, typically very close to their ETFs.

Source: worked for a brokerage and mutual fund company


One reason is that it is not possible (at Vanguard and at many other brokerages) to auto-invest into ETFs. Because the ETF trades like a stock, you typically must buy a whole number of shares. This makes it difficult to do auto-investing where you invest, say, a fixed dollar amount each month. If you're investing $100 and the ETF trades for $30 a share, you must either buy 3 shares and leave $10 unspent, or buy 4 and spend $20 more than you planned. This makes auto-investing with dollar amounts difficult. (It would be cool if there were brokerages that handled this for you, for instance by accumulating "leftover" cash until an additional whole share could be purchased, but I don't know of any.)

A difference of 0.12% in the expense ratios is real, but small. It may be outweighed by the psychological gains of being able to adopt a "hands-off" auto-investing plan. With ETFs, you generally must remember to "manually" buy the shares yourself every so often. For many average investors, the advantage of being able to invest without having to think about it at all is worth a small increase in expense ratio. The 0.12% savings don't do you any good if you never remember to buy shares until the market is already up.

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