Function and purpose

The stock market is one of the most important sources for companies to raise money. This allows businesses to go public, or raise additional capital for expansion. The liquidity that an exchange provides affords investors the ability to quickly and easily sell securities. This is an attractive feature of investing in stocks, compared to other less liquid investments such as real estate.

History has shown that the price of shares and other assets is an important part of the dynamics of economic activity, and can influence or be an indicator of social mood. Rising share prices, for instance, tend to be associated with increased business investment and vice versa. Share prices also affect the wealth of households and their consumption. Therefore, central banks tend to keep an eye on the control and behavior of the stock market and, in general, on the smooth operation of financial system functions. Financial stability is the raison d'être of central banks.

Exchanges also act as the clearinghouse for each transaction, meaning that they collect and deliver the shares, and guarantee payment to the seller of a security. This eliminates the risk to an individual buyer or seller that the counterparty could default on the transaction.

The smooth functioning of all these activities facilitates economic growth in that lower costs and enterprise risks promote the production of goods and services as well as employment. In this way the financial system contributes to increased prosperity.

Relation of the stock market to the modern financial system

The financial system in most western countries has undergone a remarkable transformation. One feature of this development is disintermediation. A portion of the funds involved in saving and financing flows directly to the financial markets instead of being routed via banks' traditional lending and deposit operations. The general public's heightened interest in investing in the stock market, either directly or through mutual funds, has been an important component of this process. Statistics show that in recent decades shares have made up an increasingly large proportion of households' financial assets in many countries. In the 1970s, in Sweden, deposit accounts and other very liquid assets with little risk made up almost 60 per cent of households' financial wealth, compared to less than 20 per cent in the 2000s. The major part of this adjustment in financial portfolios has gone directly to shares but a good deal now takes the form of various kinds of institutional investment for groups of individuals, e.g., pension funds, mutual funds, hedge funds, insurance investment of premiums, etc. The trend towards forms of saving with a higher risk has been accentuated by new rules for most funds and insurance, permitting a higher proportion of shares to bonds. Similar tendencies are to be found in other industrialized countries. In all developed economic systems, such as the European Union, the United States, Japan and other developed nations, the trend has been the same: saving has moved away from traditional (government insured) bank deposits to more risky securities of one sort or another.

The stock market, individual investors, and financial risk

Riskier long-term saving requires that an individual possess the ability to manage the associated increased risks. Stock prices fluctuate widely, in marked contrast to the stability of (government insured) bank deposits or bonds. This is something that could affect not only the individual investor or household, but also the economy on a large scale. The following deals with some of the risks of the financial sector in general and the stock market in particular. This is certainly more important now that so many newcomers have entered the stock market, or have acquired other 'risky' investments (such as 'investment' property, i.e., real estate and collectables).

With each passing year, the noise level in the stock market rises. Television commentators, financial writers, analysts, and market strategists are all overtalking each other to get investors' attention. At the same time, individual investors, immersed in chat rooms and message boards, are exchanging questionable and often misleading tips. Yet, despite all this available information, investors find it increasingly difficult to profit. Stock prices skyrocket with little reason, then plummet just as quickly, and people who have turned to investing for their children's education and their own retirement become frightened. Sometimes there appears to be no rhyme or reason to the market, only folly.

From experience we know that investors may temporarily pull financial prices away from their long term trend level. Over-reactions may occur—so that excessive optimism (euphoria) may drive prices unduly high or excessive pessimism may drive prices unduly low. New theoretical and empirical arguments have been put forward against the notion that financial markets are efficient.

According to the efficient market hypothesis (EMH), only changes in fundamental factors, such as profits or dividends, ought to affect share prices. (But this largely theoretic academic viewpoint also predicts that little or no trading should take place—contrary to fact—since prices are already at or near equilibrium, having priced in all public knowledge.) But the efficient-market hypothesis is sorely tested by such events as the stock market crash in 1987, when the Dow Jones index plummeted 22.6 percent—the largest-ever one-day fall in the United States. This event demonstrated that share prices can fall dramatically even though, to this day, it is impossible to fix a definite cause: a thorough search failed to detect any specific or unexpected development that might account for the crash. It also seems to be the case more generally that many price movements 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 confirms this.^[3] Moreover, while the EMH predicts that all price movement (in the absence of change in fundamental information) is random (i.e., non-trending), many studies have shown a marked tendency for the stock market to trend over time periods of weeks or longer.

Various explanations for large price movements have been promulgated. For instance, some research has shown that changes in estimated risk, and the use of certain strategies, such as stop-loss limits and Value at Risk limits, theoretically could cause financial markets to overreact.