Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Would investing equally in all 30 companies which comprise the DJIA net the same performance as the DJIA?
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.