Buying an ETF vs. The explicit Index
what reason would I have in buying an ETF? Apart from the efforts, the real reason is the ticket size. One can't buy shares in fraction. To truly reflect the index in equal weight, the amount to invest will be in multiples of millions [depending on the Index and the stock composition]   This related question should help you understand why it is difficult even for large fund house to exactly mimic the index. Why do passive ETFs require so much trading (and incur costs)? To add to Dheer's point, the vast majority of retail investors will have to pay fees and use up a large amount of valuable time on the entrance and exit of each stock, and each and every time you rebalance as the index weightings change. These also add up extremely fast vs the few basis points the large and liquid ETFs charge for this service.
One difference is the bid/ask spread will cost you more in a lower cost stock than a higher cost one. Say you have two highly liquid stocks with tiny spreads: If you wanted to buy say $2,000 of stock: Now imagine these are almost identical ETFs tracking the S&P 500 index and extrapolate this to a trade of $2,000,000 and you can see there's some cost savings in the higher priced stock. As a practical example, recently a popular S&P 500 ETF (Vanguard's VOO) did a reverse split to help investors minimize this oft-missed cost. "Following comments to your question here, you posted a separate question about why SPY, SPX, and the options contract don't move perfectly together.  That's here Why don't SPY, SPX, and the e-mini s&p 500 track perfectly with each other? I provided an answer to that question and will build on it to answer what I think you're asking on this question.  Specifically, I explained what it means that these are ""all based on the S&P.""  Each is a different entity, and different market forces keep them aligned.  I think talking about ""technicals"" on options contracts is going to be too confusing since they are really a very different beast based on forward pricing models, so, for this question, I'll focus on only SPY and SPX. As in my other answer, it's only through specific market forces (the creation / redemption mechanism that I described in my other answer), that they track at all.  There's nothing automatic about this and it has nothing to do with some issuer of SPY actually holding stock in the companies that comprise the SPX index. (That's not to say that the company does or doesn't hold, just that this doesn't drive the prices.)  What ever technical signals you're tracking, will reflect all of the market forces at play.  For SPX (the index), that means some aggregate behavior of the component companies, computed in a ""mathematically pure"" way.  For SPY (the ETF), that means (a) the behavior of SPX and (b) the behavior of the ETF as it trades on the market, and (c) the action of the authorized participants.  These are simply different things. Which one is ""right""?  That depends on what you want to do.  In theory you might be able to do some analysis of technical signals on SPY and SPX and, for example, use that to make money on the way that they fail to track each other.  If you figure out how to do that, though, don't post it here.  Send it to me directly. :)" There are times when investing in an ETF is more convenient than a mutual fund. When you invest in a mutual fund, you often have an account directly with the mutual fund company, or you have an account with a mutual fund broker.  Mutual funds often have either a front end or back end load, which essentially gives you a penalty for jumping in and out of funds. ETFs are traded exactly like stocks, so there is inherently no load when buying or selling.  If you have a brokerage account and you want to move funds from a stock to a mutual fund, an ETF might be more convenient. With some accounts, an ETF allows you to invest in a fund that you would not be able to invest in otherwise.  For example, you might have a 401k account through your employer.  You might want to invest in a Vanguard mutual fund, but Vanguard funds are not available with your 401k.  If you have access to a brokerage account inside your 401k, you can invest in the Vanguard fund through the associated ETF. Another reason that you might choose an ETF over a mutual fund is if you want to try to short the fund. The expense ratio reduces the return of the ETF; your scenario of paying 100.0015 is that of a load.  Most (all?) ETFs can be bought without paying a load (sales charge as a percent of amount invested), and some ETFs can be bought without paying a brokerage fee (fixed or variable charge for a buy transaction just like buying any other stock  through the brokerage) because the brokerage has waived it.  Your broker  might charge fees for both buying and selling shares in an ETF, but in any case, this is quite separate from the expense ratio. ETFs are a type of investment, not a specific choice. In other words, there are good ETFs and bad. What you see is the general statement that ETFs are preferable to most mutual funds, if only for the fact that they are low cost. An index ETF such as SPY (which reflects the S&P 500 index) has a .09% annual expense, vs a mutual fund which average a full percent or more.  sheegaon isn't wrong, I just have a different spin to offer you. Given a long term return of say even 8% (note - this question is not a debate of the long term return, and I purposely chose a low number compared to the long term average, closer to 10%) and the current CD rate of <1%, a 1% hit for the commission on the buy side doesn't bother me. The sell won't occur for a long time, and $8 on a $10K sale is no big deal. I'd not expect you to save $1K/yr in cash/CDs for the years it would take to make that $8 fee look tiny. Not when over time the growth will overshaddow this.  One day you will be in a position where the swings in the market will produce the random increase or decrease to your net worth in the $10s of thousands. Do you know why you won't lose a night's sleep over this? Because when you invested your first $1K, and started to pay attention to the market, you saw how some days had swings of 3 or 4%, and you built up an immunity to the day to day noise. You stayed invested and as you gained wealth, you stuck to the right rebalancing each year, so a market crash which took others down by 30%, only impacted you by 15-20, and you were ready for the next move to the upside. And you also saw that since mutual funds with their 1% fees never beat the index over time, you were happy to say you lagged the S&P by .09%, or 1% over 11 year's time vs those whose funds had some great years, but lost it all in the bad years.  And by the way, right until you are in the 25% bracket, Roth is the way to go. When you are at 25%, that's the time to use pre-tax accounts to get just below the cuttoff.  Last, welcome to SE.    Edit - see sheegaon's answer below. I agree, I missed the cost of the bid/ask spread. Going with the lowest cost (index) funds may make better sense for you.  To clarify, Sheehan points out that ETFs trade like a stock, a commission, and a bid/ask, both add to transaction cost. So, agreeing this is the case, an indexed-based mutual fund can provide the best of possible options. Reflecting the S&P (for example) less a small anual expense, .1% or less. 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 Index Funds & ETFs, if they are tracking the same index, will be the same in an ideal world. The difference would be because of the following factors: Expense ratio: i.e. the expense the funds charge. This varies and hence it would lead to a difference in performance. Tracking error: this means that there is a small percentage of error between the actual index composition and the fund composition. This is due to various reasons.  Effectively this would result in the difference between values. Demand / Supply: with ETFs, the fund is traded on stock exchanges like a stock. If the general feeling is that the index is rising, it could lead to an increase in the price of the ETF. Index funds on the other hand would remain the same for the day and are less liquid. This results in a price increase / decrease depending on the market. The above explains the reason for the difference.   Regarding which one to buy, one would need to consider other factors like: a) How easy is it to buy ETFs? Do you already hold Demat A/C & access to brokers to help you conduct the transaction or do you need to open an additional account at some cost. b) Normally funds do not need any account, but are you OK with less liquidity as it would take more time to redeem funds. Yes, it depends on the fund it's trying to mirror.  The ETF for the S&P that's best known (in my opinion) is SPY and you see the breakdown of its holdings.  Clearly, it's not an equal weighted index. "I'm assuming the question is about how to compare two ETFs that track the same index. I'd look at (for ETFs -- ignoring index funds): So, for example you might compare SPY vs IVV: SPY has about 100x the volume. Sure, IVV has 2M shares trading, so it is liquid ""enough"". But the bigger volume on SPY might matter to you if you use options: open interest is as much as 1000x more on SPY. Even if you have no interest in options, the spreads on SPY are probably going to be slightly smaller. They both have 0.09% expense ratios. When I looked on 2010-9-6, SPY was trading at a slight discount, IVV was at a slight premium. Looking for any sort of trend is left as an exercise to the reader... Grab the prospectus for each to examine the rules they set for fund makeup. Both come from well-known issuers and have a decent history. (Rather than crazy Uncle Ed's pawn shop, or the Central Bank of Stilumunistan.) So unless you find something in the SPY prospectus that makes you queasy, the higher volume and equal expense ratios would seem to suggest it over IVV. The fact that it is at a (tiny) discount right now is a (tiny) bonus." But if you add a security to the index you also remove one from the index, thus both a buy and sell. If weights change some go up, some go down thus some need to be purchased and some need to be sold.   So I still don't see how ETFs are net sinks beyond their simple AUM. In my opinion, the ability to set a sell or buy price is the least of my concerns.  Your question of whether to choose individual stocks vs funds prompts a different issue for me to bring to light. Choosing stocks that beat the market is not simple. In fact, a case can be made for the fact that the average fund lags the market by more and more over time. In the end, conceding that fact and going with the lowest cost funds or ETFs will beat 90% of investors over time. No, some of Vanguard's funds are index funds like their Total Stock Market Index and 500 Index. In contrast, there are funds like Vanguard PRIMECAP and Vanguard Wellington that are actively managed. There are index funds in both open-end and exchange-traded formats. VTI is the ticker for Vanguard's Total Stock Market ETF while VTSMX is an open-end mutual fund format. VOO would be the S & P 500 ETF ticker while VFINX is one of the open-end mutual fund tickers, where VIIIX has a really low expense ratio but a pretty stiff minimum to my mind. As a general note, open-end mutual funds will generally have a 5 letter ticker ending in X while an ETF will generally be shorter at 3 or 4 letters in length. With the disclaimer that I am not a technician, I'd answer yes, it does. SPY (for clarification, an ETF that reflects the S&P 500 index) has dividends, and earnings, therefore a P/E and dividend yield. It would follow that the tools technicians use, such as moving averages, support and resistance levels also apply.  Keep in mind, each and every year, one can take the S&P stocks and break them up, into quintiles or deciles based on return and show that not all stock move in unison. You can break up by industry as well which is what the SPDRs aim to do, and observe the movement of those sub-groups.  But, no, not all the stocks will perform the way the index is predicted to.  (Note - If a technician wishes to correct any key points here, you are welcome to add a note, hopefully, my answer was not biased) "For US stocks it's a bit of a gamble. Many actively managed funds underperform the market indexes, but some of them outperform in many years. With an index you will get average results. With an active manager you ""might"" do better than average. So you can view active management as a higher risk, potentially higher reward investment approach. On the other hand, if you want to diversify some of your investments into international stocks, bonds, junk bonds, and real estate (REITs) active management is highly likely to be better than indexing. For these specialized areas specialized knowledge and research is needed." You better buy an ETF that does the same, because it would be much cheaper than mutual fund (and probably much cheaper than doing it yourself and rebalancing to keep up with the index).  Look at DIA for example. Neither buying the same amount of stocks nor buying for the same amount of money would be tracking the DJIE. The proportions are based on the market valuation of each of the companies in the index.