Additionally, many choose to invest via the index method. In this method, one holds a weighted or unweighted portfolio consisting of the entire stock market or some segment of the stock market (such as the S&P 500 or Wilshire 5000). The principal aim of this strategy is to maximize diversification, minimize taxes from too frequent trading, and ride the general trend of the stock market (which, in the U.S., has averaged nearly 10% per year, compounded annually, since World War II).
This event demonstrated that share prices can fall dramatically even though no generally agreed upon definite cause has been found: a thorough search failed to detect any 'reasonable' development that might have accounted for the crash. (Note that such events are predicted to occur strictly by chance, although very rarely.) It seems also to be the case more generally that many price movements (beyond that which are predicted to occur 'randomly') are not occasioned by new information; a study of the fifty largest one-day share price movements in the United States in the post-war period seems to confirm this.
The exchange also earns from selling market data generated on its platform - like real-time data, historical data, summary data, and reference data – which is vital for equity research and other uses. Many exchanges will also sell technology products, like a trading terminal and dedicated network connection to the exchange, to the interested parties for a suitable fee.
Research is provided for informational purposes only, does not constitute advice or guidance, nor is it an endorsement or recommendation for any particular security or trading strategy. Research is provided by independent companies not affiliated with Fidelity. Please determine which security, product, or service is right for you based on your investment objectives, risk tolerance, and financial situation. Be sure to review your decisions periodically to make sure they are still consistent with your goals.