Would investing equally in all 30 companies which comprise the DJIA net the same performance as the DJIA?
"DJIA is a price weighted index (as in the amount of each component company is weighted by its price) and the constituents change occasionally (51 times so far). With these two effects you would not get anything like the same return by equally weighting your holdings and would have to rebalance every so often. Note that your premise was most obviously flawed thinking the number of near bankruptcies there have been in that time. More details of the differing make-ups of the index are available on Wikipedia. When you ask about the ""average investment"" you would have to be a lot more specific; is it limited just to US shares, to shares, to shares and fixed income securities, should I include all commodities, etc. see also What's the justification for the DJIA being share-price weighted?" "MD-Tech's answer is correct. Let me only point out that there are easier ways to invest in the DJIA index without having to buy individual stocks. You can buy a mutual fund or ETF that will track the index and your return will be almost identical to the performance of the underlying index. It's ""almost"" identical because the fund will take a small management fee, you will have to pay annual taxes on capital gains (if you hold the investment in a taxable account), and because the fund has to actually invest in the underlying stocks, there will be small differences due to rounding and timing of the fund's trades. You also ask: Assuming that I calculated those numbers correctly, is this gain   approximately better, equal to, or worse than an average investment   for that timespan? While people argue about the numbers, index funds tend to do better than average (depends on what you call ""average"", of course). They do better than most actively managed funds, too. And since they have low management fees, index funds are often considered to be an important part of a long-term investment portfolio because they require very little activity on your part other than buying and holding."
Well, you can just say that 1 dollar contributed = one share and pay out dividends based on number of shares. That makes it pretty easy to make things fair based. There are pros and cons with this pooling approach. The reason for such differences is that there's no source to get this information. The companies do not (and cannot) report who are their shareholders except for large shareholders and stakes of interest. These, in the case of GoPro, were identified during the IPO (you can look the filings up on EDGAR). You can get information from this or that publicly traded mutual fund about their larger holdings from their reports, but private investors don't provide even that. Institutional (public) investors buy and sell shares all the time and only report large investments. So there's no reliable way to get a snapshot picture you're looking for. The details of the DJIA methodology is outlined in the official methodology document on their website.  In addition, you will need their index mathematics document, which gives the nitty-gritty details of any type of adjustments that must be made. Between the two you should have the complete picture in as fine a detail as you want, including exactly what is done in response to various corporate actions like splits and structural changes. "I hope a wall of text with citations qualifies as ""relatively easy."" Many of these studies are worth quoting at length. Long story short, a great deal of research has found that actively-managed funds underperform market indexes and passively-managed funds because of their high turnover and higher fees, among other factors.  Longer answer: Chris is right in stating that survivorship bias presents a problem for such research; however, there are several academic papers that address the survivorship problem, as well as the wider subject of active vs. passive performance. I'll try to provide a brief summary of some of the relevant literature.  The seminal paper that started the debate is Michael Jensen's 1968 paper titled ""The Performance of Mutual Funds in the Period 1945-1964"". This is the paper where Jensen's alpha, the ubiquitous measure of the performance of mutual fund managers, was first defined. Using a dataset of 115 mutual fund managers, Jensen finds that The evidence on mutual fund performance indicates not only that these 115 mutual funds were on average not able to predict security prices well enough to outperform a buy-the-market-and-hold policy, but also that there is very little evidence that any individual fund was able to do significantly better than that which we expected from mere random chance. Although this paper doesn't address problems of survivorship, it's notable because, among other points, it found that managers who actively picked stocks performed worse even when fund expenses were ignored. Since actively-managed funds tend to have higher expenses than passive funds, the actual picture looks even worse for actively managed funds. A more recent paper on the subject, which draws similar conclusions, is Martin Gruber's 1996 paper ""Another puzzle: The growth in actively managed mutual funds"". Gruber calls it ""a puzzle"" that investors still invest in actively-managed funds, given that their performance on average has been inferior to that of index funds. He addresses survivorship bias by tracking funds across the entire sample, including through mergers. Since most mutual funds that disappear are merged into existing funds, he assumes that investors in a fund that disappear choose to continue investing their money in the fund that resulted from the merger. Using this assumption and standard measures of mutual fund performance, Gruber finds that mutual funds underperform an appropriately weighted average of the indices by about 65 basis points per year. Expense ratios for my sample averaged 113 basis points a year. These numbers suggest that active management adds value, but that mutual funds charge the investor more than the value added. Another nice paper is Mark Carhart's 1997 paper ""On persistence in mutual fund performance"" uses a sample free of survivorship bias because it includes ""all known equity funds over this period."" It's worth quoting parts of this paper in full: I demonstrate that expenses have at least a one-for-one negative impact on fund performance, and that turnover also negatively impacts performance. ... Trading reduces performance by approximately 0.95% of the trade's market value.  In reference to expense ratios and other fees, Carhart finds that The investment costs of expense ratios, transaction costs, and load fees all have a direct, negative impact on performance. The study also finds that funds with abnormally high returns last year usually have higher-than-expected returns next year, but not in the following years, because of momentum effects. Lest you think the news is all bad, Russ Wermer's 2000 study ""Mutual fund performance: An empirical decomposition into stock‐picking talent, style, transactions costs, and expenses"" provides an interesting result. He finds that many actively-managed mutual funds hold stocks that outperform the market, even though the net return of the funds themselves underperforms passive funds and the market itself.  On a net-return level, the funds underperform broad market indexes by one percent a year. Of the 2.3% difference between the returns on stock holdings and the net returns of the funds, 0.7% per year is due to the lower average returns of the nonstock holdings of the funds during the period (relative to stocks). The remaining 1.6% per year is split almost evenly between the expense ratios and the transaction costs of the funds. The final paper I'll cite is a 2008 paper by Fama and French (of the Fama-French model covered in business schools) titled, appropriately, ""Mutual Fund Performance"". The paper is pretty technical, and somewhat above my level at this time of night, but the authors state one of their conclusions bluntly quite early on: After costs (that is, in terms of net returns to investors) active investment is a negative sum game.  Emphasis mine. In short, expense ratios, transaction costs, and other fees quickly diminish the returns to active investment. They find that The [value-weight] portfolio of mutual funds that invest primarily in U.S. equities is close to the market portfolio, and estimated before fees and expenses, its alpha is close to zero. Since the [value-weight] portfolio of funds produces an α close to zero in gross returns, the alpha estimated on the net returns to investors is negative by about the amount of fees and expenses. This implies that the higher the fees, the farther alpha decreases below zero. Since actively-managed mutual funds tend to have higher expense ratios than passively-managed index funds, it's safe to say that their net return to the investor is worse than a market index itself. I don't know of any free datasets that would allow you to research this, but one highly-regarded commercial dataset is the CRSP Survivor-Bias-Free US Mutual Fund Database from the Center for Research in Security Prices at the University of Chicago. In financial research, CRSP is one of the ""gold standards"" for historical market data, so if you can access that data (perhaps for a firm or academic institution, if you're affiliated with one that has access), it's one way you could run some numbers yourself." If you mean the percentages of long/short positions within a mutual fund or ETF, then it's a percentage of the total value of the fund portfolio. In that case, positions of 50% in X, -50% in Y are not the same as 100% in X, -100% in Y. If the long and short positions are both for the same asset, then, as D Stanley mentions, all that matters is the net position. If you're equally long and short X, then the net position is always 0%. In answer to your last formulation, no. In a perfectly efficient market, different investors still have different risk tolerances (or utility functions). They're maximizing expected utility, not expected value.  The portfolios that maximize expected utility for different risk preferences are different, and thus generally have different expected values. (Look up mean-variance utility for a simple-ish example.)  Suppose you have log utility for money, u(x) = log(x), and your choice is to invest all of your money in either the risk-free bond or in the risky bond. In the risky bond, you have a positive probability of losing everything, achieving utility u(0) = -\infty. Your expected utility after purchase of the risky bond is:  Pr(default)*u(default) + (1-Pr(default))*u(nominalValue).  Since u(default)= -\infty, your expected utility is also negative infinity, and you would never make this investment. Instead you would purchase the risk-free bond.  But another person might have linear utility, u(x) = x, and he would be indifferent between the risk-free and risky bonds at the prices you mention above and might therefore purchase some. (In fact you probably would have bid up the price of the risk-free bond, so that the other investor strictly prefers the risky one.) So two different investors' portfolios will have different expected returns, in general, because of their different risk preferences. Risk-averse investors get lower expected value. This should be very intuitive from portfolio theory in general: stocks have higher expected returns, but more variance. Risk-tolerant people can accept more stocks and more variance, risk-averse people purchase less stocks and more bonds. The more general question about risk premia requires an equilibrium price analysis, which requires assumptions about the distribution of risk preferences among other things. Maybe John Cochrane's book would help with that---I don't know anything about financial economics. I would think that in the setup above, if you have positive quantities of these two investor types, the risk-free bond will become more expensive, so that the risky one offers a higher expected return. This is the general thing that happens in portfolio theory. Anyway. I'm not a financial economist or anything.  Here's a standard introduction to expected utility theory: http://web.stanford.edu/~jdlevin/Econ%20202/Uncertainty.pdf "I find it interesting that you didn't include something like [Total Bond Market](http://stockcharts.com/freecharts/perf.html?VBMFX), or [Intermediate-Term Treasuries](http://stockcharts.com/freecharts/perf.html?VBIIX), in your graphic.   If someone were to have just invested in the DJI or SP500, then they would have ignored the tenants of the Modern Portfolio Theory and not diversified adequately.  I wouldn't have been able to stomach a portfolio of 100% stocks, commodities, or metals.  My vote goes for: 1.) picking an asset allocation that reflects your tolerance for risk (a good starting point is ""age in bonds,"" i.e. if you're 30, then hold 30% in bonds); 2.) save as if you're not expecting annualized returns of %10 (for example) and save more; 3.) don't try to pick the next winner, instead broadly invest in the market and hold it.  Maybe gold and silver are bubbles soon to burst -- I for one don't know.  I don't give the ""notion in the investment community"" much weight -- as it always is, someday someone will be right, I just don't know who that someone is." "For the S&P and many other indices (but not the DJIA) the index ""price"" is just a unitless number that is the result of a complicated formula.  It's not a dollar value.  So when you divide said number by the earnings/share of the sector, you're again getting just a unitless number that is incomparable to standard P-E ratios. In fact, now that I think about, it kinda makes sense that each sector would have a similar value for the number that you're computing, since each sector's index formula is presumably written to make all the index ""price""s look similar to consumers." and seems to do better than the S&P 500 too. No, that's not true. In fact, this fund is somewhere between S&P500 and the NASDAQ Composite indexes wrt to performance. From my experience (I have it too), it seems to fall almost in the middle between SPY and QQQ in daily moves. So it does provide diversification, but you're basically diversifying between various indexes. The cost is the higher expense ratios (compare VTI to VOO). All forms of liquid investing necessarily have the same expected value. If any one form were more profitable, money would flood in, equalizing it. Day trading is unusual in two key ways. First, although the expected value is the same, the risk profile is very different. For example, would you wager a dollar on the flip of a coin?  You might.  Why not, after all? Would you wager a million dollars?  Probably not. The risk is too great. Similarly, day trading can easily lose you all of your investment, which is why you should be careful doing it. (In his memoirs Liar's Poker, Michael Lewis tells an anecdote about a rich bond trader who proposes a million-dollar, even-money bet with his rival, an amount both could just barely afford to lose.  The rival, not wanting to play but not wanting to lose face by declining, accepted.. with the proviso that the stakes be raised to 10 million dollars! The trader backed down.) Also, the efficient market only guarantees the price will be efficient.  It says nothing about transaction costs.  A busy day-trader can easily incur thousands in commission and other fees. "when the index is altered to include new players/exclude old ones, the fund also adjusts The largest and (I would say) most important index funds are whole-market funds, like ""all-world-ex-US"", or VT ""Total World Stock"", or ""All Japan"".  (And similarly for bonds, REITS, etc.)  So companies don't leave or enter these indexes very often, and when they do (by an initial offering or bankruptcy) it is often at a pretty small value. Some older indices like the DJIA are a bit more arbitrary but these are generally not things that index funds would try to match. More narrow sector or country indices can have more of this effect, and I believe some investors have made a living from index arbitrage.  However well run index funds don't need to just blindly play along with this. You need to remember that an index fund doesn't need to hold precisely every company in the index, they just need to sample such that they will perform very similarly to the index.  The 500th-largest company in the S&P 500 is not likely to have all that much of an effect on the overall performance of the index, and it's likely to be fairly correlated to other companies in similar sectors, which are also covered by the index.  So if there is a bit of churn around the bottom of the index, it doesn't necessarily mean the fund needs to be buying and selling on each transition.  If I recall correctly it's been shown that holding about 250 stocks gives you a very good match with the entire US stock market." Is it POSSIBLE? Of course. I don't even need to do any research to prove that. Just some mathematical reasoning: Take the S&P 500. Find the performance of each stock in that list over whatever time period you want to use for your experiment. Now select some number of the best-performing stocks from the list -- any number less than 500. By definition, the X best must be better than or equal to the average. Assuming all the stocks on the S&P did not have EXACTLY the same performance, these 10 must be better than average. You now have a diversified portfolio that performed better than the S&P 500 index fund. Of course as they always say in a prospectus, past performance is not a guarantee of future performance.  It's certainly possible to do. The question is, if YOU selected the stocks making up a diversified portfolio, would your selections do better than an index fund? Conglomerates don't work. We've seem thay countless times in countless periods in countless places in history... A focused company will always outperform an unfocused company in the long run...     Grocery stores trade at tiny multiples. Tech firms at massive multiples. The instant you buy a 3x EBITDA when you're trading at 15x EBITDA, you've increased the market value of the acquired firm by 5x... As these all seem to be US Equity, just getting one broad based US Equity index might offer similar diversification at lower cost. Over 5 years, 20 basis points in fees will only make about 1% difference. However, for longer periods (retirement saving), it is worth it to aim for the lowest fees. For further diversification, you might want to consider other asset classes, such as foreign equity, fixed income, etc. 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.