Why would a long-term investor ever chose a Mutual Fund over an ETF?
First, it's not always the case that ETFs have lower expenses than the equivalent mutual funds.  For example, in the Vanguard family of funds the expense ratio for the ETF version is the same as it is for the Admiral share class in the mutual fund version.  With that in mind, the main advantages of a mutual fund over an equivalent ETF are: From a long-term investor's point of view, the main disadvantage of mutual funds relative to ETFs is the minimum account sizes.  Especially if the fund has multiple share classes (i.e., where better classes get lower expense ratios), you might have to have quite a lot of money invested in the fund in order to get the same expense ratio as the ETF.   There are some other differences that matter to more active investors (e.g., intraday trading, options, etc.), but for a passive investor the ones above are the major ones.  Apart from those mutual funds and ETFs are pretty similar.  Personally, I prefer mutual funds because I'm at a point where the fund minimums aren't really an issue, and I don't want to deal with the more fiddly aspects of ETFs. For investors just starting out the lower minimum investment for an ETF is a big win, as long as you can get commission-free trades (which is what I've assumed above.) I see a couple of reasons why you could consider choosing a mutual fund over an ETF In some cases index mutual funds can be a cheaper alternative to ETFs. In the UK where I am based, Fidelity is offering a management fee of 0.07% on its FTSE All shares tracker. Last time I checked, no ETF was beating that There are quite a few cost you have to foot when dealing ETFs In some cases, when dealing for relatively small amounts (e.g. a monthly investment plan) you can get a better deal, if your broker has negotiated discounts for you with a fund provider. My broker asks £12.5 when dealing in shares (£1.5 for the regular investment plan) whereas he asks £0 when dealing in funds and I get a 100% discount on the initial charge of the fund. As a conclusion, I would suggest you look at the all-in costs over total investment period you are considering for the exact amount you are planning to invest. Despite all the hype, ETFs are not always the cheapest alternative. http://www.efficientfrontier.com/ef/104/stupid.htm would have some data though a bit old about open-end funds vs an ETF that would be one point. Secondly, do you know that the Math on your ETF will always work out to whole numbers of shares or do you plan on using brokers that would allow fractional shares easily? This is a factor as $3,000 of an open-end fund will automatically go into fractional shares that isn't necessarily the case of an ETF where you have to specify a number of shares when you purchase as well as consider are you doing a market or limit order? These are a couple of things to keep in mind here. Lastly, what if the broker you use charges account maintenance fees for your account? In buying the mutual fund from the fund company directly, there may be a lower likelihood of having such fees. I don't know of any way to buy shares in the ETF directly without using a broker. There is little difference between buying shares in your broker's index fund and shares of their corresponding ETF.  In many cases the money invested in an ETF gets essentially stuffed right into the index fund (I believe Vanguard does this, for example).  In either case you will be paying a little bit of tax.  In the ETF case it will be on the dividends that are paid out.  In the index fund case it will additionally be on the capital gains that have been realized within the fund, which are very few for an index fund.  Not a ton in either case.  The more important tax consideration is between purchase and sale, which is the same in either case. I'd say stick it wherever the lowest fees are.
In my opinion, if you are doing long-term investing, this is a non-issue.  The difference of hours in being able to trade an ETF during the day vs. only being able to trade a traditional mutual fund at day-end is irrelevant if you are holding the investment for a long time. If you are engaging in day trading, market timing, or other advanced/controversial trading practices, then I suppose it could make a difference. For the way I invest (index funds, long-term, set-it-and-forget-it), ETFs have no advantage over traditional mutual funds. The mutual fund will price at day's end, while the ETF trades during the day, like a stock. If you decide at 10am, that some event will occur during the day that will send the market up, the ETF is preferable. Aside from that, the expenses are identical, a low .14%. No real difference especially in a Roth. "The majority (about 80%) of mutual funds are underperforming their underlying indexes. This is  why ETFs have seen massive capital inflows compared to equity funds, which have seen significant withdrawals in the last years.  I would definitively recommend going with an ETF. In addition to pure index based ETFs that (almost) track broad market indexes like the S&P 500 there are quite a few more ""quant"" oriented ETFs that even outperformed the S&P. I am long the S&P trough iShares ETFs and have dividend paying ETFs and some quant ETFS on top (Invesco Powershares) in my portfolio." Right now, the unrealized appreciation of Vanguard Tax-Managed   Small-Cap Fund Admiral Shares is 28.4% of NAV. As long as the fund   delivers decent returns over the long term, is there anything stopping   this amount from ballooning to, say, 90% fifty years hence? I'd have a heck of a time imagining how this grows to that high a number realistically.  The inflows and outflows of the fund are a bigger question along with what kinds of changes are there to capital gains that may make the fund try to hold onto the stocks longer and minimize the tax burden. If this happens, won't new investors be scared away by the prospect of   owing taxes on these gains? For example, a financial crisis or a   superior new investment technology could lead investors to dump their   shares of tax-managed index funds, triggering enormous capital-gains   distributions. And if new investors are scared away, won't the fund be   forced to sell its assets to cover redemptions (even if there is no   disruptive event), leading to larger capital-gains distributions than   in the past? Possibly but you have more than a few assumptions in this to my mind that I wonder how well are you estimating the probability of this happening. Finally, do ETFs avoid this problem (assuming it is a problem)? Yes, ETFs have creation and redemption units that allow for in-kind transactions and thus there isn't a selling of the stock.  However, if one wants to pull out various unlikely scenarios then there is the potential of the market being shut down for an extended period of time that would prevent one from selling shares of the ETF that may or may not be as applicable as open-end fund shares. I would however suggest researching if there are hybrid funds that mix open-end fund shares with ETF shares which could be an alternative here. The main difference between a mutual fund and an ETF are how they are bought and sold (from the investors perspective). An ETF is transacted on the open market. This means you normally can't buy partial shares with your initial investment. Having to transact on the open market also means you pay a market price. The market price is always a little bit different from the Net Asset Value (NAV) of the fund. During market hours, the ETF will trade at a premium/discount to the NAV calculated on the previous day. Morningstar's fund analysis will show a graph of the premium/discount to NAV for an ETF. With a mutual fund on the other hand, your investment goes to a fund company, which then grants you shares while under the hood buying the underlying investments. You pay the NAV price and are allowed to buy partial shares. Usually an ETF has a lower expense ratio, but if that's equal and any initial fees/commissions are equal, I would prefer the mutual fund in order to buy partial shares (so your initial investment will be fully invested) and so you don't have to worry about paying premium to NAV ETFs are both liquid (benefits active traders) and a simple way for people to invest in funds even if they don't have the minimum balance needed to invest in a mutual fund (EDIT: in which purchases are resolved at the end of the trading day). One big difference between ETFs and mutual funds is that you must buy ETFs in whole units, whereas you can add $100 to a mutual fund and the fund will determine -- usually to 4 decimal places -- how many shares you've purchased. Wikipedia has a fairly detailed explanation of ETFs.  http://en.wikipedia.org/wiki/Exchange-traded_fund "Why bother with the ETF? Just trade the options -- at least you have the ability to know what you actually are doing. The ""exotic"" ETFs the let you ""double long"" or short indexes aren't options contracts -- they are just collections of unregulated swaps with no transparency. Most of the short/double long ETFs also only attempt to track the security over the course of one day -- you are supposed to trade them daily. Also, you have no guarantee that the ETFs will perform as desired -- even during the course of a single day. IMO, the simplicity of the ETF approach is deceiving." A mutual fund has several classes of shares that are charged different fees. Some shares are sold through brokers and carry a sales charge (called load) that compensates the broker in lieu of a fee that the broker would charge the client for the service.  Vanguard does not have sales charge on its funds and you don't need to go through a broker to buy its shares; you can buy directly from them.  Admiral shares of Vanguard funds are charged lower annual expenses than regular shares (yes, all mutual funds charge expenses for fund adninistration that reduce the return that you get, and Vanguard has some of the lowest expense ratios) but Admiral shares are available only for large investments, typically $50K or so.  If you have invested in a Vanguard mutual fund, your shares can be set to automatically convert to Admiral shares when the investment reaches the right level. A mutual fund manager can buy and sell stocks to achieve the objectives of the fund, so what stockes you are invested in as a share holder in a mutual fund will typically be unknown to you on a day-to-day basis.  On the other hand, Exchange-traded funds (ETFs) are fixed baskets of stocks, and you can buy shares in the ETF.  These shares are bought and sold through a broker (so you pay a transaction fee each time) but expenses are lower since there is no manager to buy and sell stocks: the basket is fixed. Many ETFs follow specific market indexes (e.g. S&P 500).  Another difference between ETFs and mutual funds is that you can buy and sell ETFs at any time of the day just as if you could if you held stocks. With mutual funds, any buy and sell requests  made during the day are processed at the end of the day and the value of the shares that you buy or sell is determined by the closing price of the stocks held by the mutual fund.  With ETFs, you are getting the intra-day price at the time the buy or sell order is executed by your broker. ETFs offer the flexibility of stocks while retaining many of the benefits of mutual funds. Since an ETF is an actual fund, it has the diversification of its potentially many underlying securities. You can find ETFs with stocks at various market caps and style categories. You can have bond or mixed ETFs. You can even get ETFs with equal or fundamental weighting. In short, all the variety benefits of mutual funds. ETFs are typically much less expensive than mutual funds both in terms of management fees (expense ratio) and taxable gains. Most of them are not actively managed; instead they follow an index and therefore have a low turnover. A mutual fund may actively trade and, if not balanced with a loss, will generate capital gains that you pay taxes on. An ETF will produce gains only when shifting to keep inline with the index or you yourself sell. As a reminder: while expense ratio always matters, capital gains and dividends don't matter if the ETF or mutual fund is in a tax-advantaged account. ETFs have no load fees. Instead, because you trade it like a stock, you will pay a commission. Commissions are straight, up-front and perfectly clear. Much easier to understand than the various ways funds might charge you. There are no account minimums to entry with ETFs, but you will need to buy complete shares. Only a few places allow partial shares. It is generally harder to dollar-cost average into an ETF with regular automated investments. Also, like trading stocks, you can do those fancy things like selling short, buying on margin, options, etc. And you can pay attention to the price fluctuations throughout the day if you really want to. Things to make you pause: if you buy (no-load) mutual funds through the parent company, you'll get them at no commission. Many brokerages have No Transaction Fee (NTF) agreements with companies so that you can buy many funds for free. Still look out for that expense ratio though (which is probably paying for that NTF advantage). As sort of a middle ground: index funds can have very low expense ratios, track the same index as an ETF, can be tax-efficient or tax-managed, free to purchase, easy to dollar-cost average and easier to automate/understand. Further reading: I choose lifecycle funds because I am placing faith (perhaps foolishly) that a full time fund manager knows better what to pick than I.  The same reason I go with mutual funds in general apply to to why I also have the lifecycle funds.  Presently my diversification strategy is really just index funds and lifecycle funds. The radio advice guy Clark Howard often promotes them. http://www.wacotrib.com/none/content/shared/money/stories/clark/0601/060425money.html (I count in the intimidated group) This is probably the best, most concise and yet detailed answer to this oft-posed question I've seen on this sub. Have an upvote. Only thing I'd add is that HFs' comparatively more active approach creates a moat vs. mutual funds, which are seen as more long-term, passive investments. This means they can charge fees and have higher expense ratios (though obviously anyone in finance who has been conscious in the last five years knows that this is changing) "There are several reasons. One, mutual funds provide instant diversification.  To build a diverse portfolio ""manually"" (by buying individual shares) requires a lot of time and effort.  If your portfolio is not diverse, then it is wrong to say ""buying shares gives higher return""; in many cases diversification will increase your returns. Two, mutual funds reduce transactions costs.  If you buy individual shares, you pay transactions costs every time you buy or sell.  If you buy and sell the shares of many companies, you must perform many transactions and thus incur heavy fees.  With mutual funds, a single transaction gets you access to many companies.  In addition, it is often possible to buy mutual funds without paying transactions costs at all (although you will still pay fund expenses). Three (sort of a combination of the previous two) it is just easier.  Many people can easily buy mutual funds with no cost and little effort through their bank.  It is also simple to set up auto-investment plans so that you automatically save money over time.  All of these things are much more complicated if you try to buy many individual shares. Four, if you buy the right kinds of funds (low-cost index funds), it is probably more lucrative than buying individual shares.  The odds that, through carefully selected stock-buying, you will earn more than the market average are small.  Even professional stock-pickers consistently underperform broad market indexes. In short, it is not true that ""buying shares gives higher return"", and even if it were, the convenience and diversification of mutual funds would still be good reasons to use them." "As Dheer pointed out, the top ten mega-cap corporations account for a huge part (20%) of your ""S&P 500"" portfolio when weighted proportionally. This is one of the reasons why I have personally avoided the index-fund/etf craze -- I don't really need another mechanism to buy ExxonMobil, IBM and Wal-Mart on my behalf. I like the equal-weight concept -- if I'm investing in a broad sector (Large Cap companies), I want diversification across the entire sector and avoid concentration. The downside to this approach is that there will be more portfolio turnover (and expense), since you're holding more shares of the lower tranches of the index where companies are more apt to churn. (ie. #500 on the index gets replaced by an up and comer). So you're likely to have a higher expense ratio, which matters to many folks." This is almost exactally what the BK attorneys I work with have always said.  If you have trouble offer a larger down payment. . . . that is the point of the down payment after all.  You do sometimes have better luck with renting from individual people rather than larger corporately owned rentals.    There are options out there.