Stock exchanges are secondary markets, where existing owners of shares can transact with potential buyers. It is important to understand that the corporations listed on stock markets do not buy and sell their own shares on a regular basis (companies may engage in stock buybacks8? or issue new shares,9? but these are not day-to-day operations and often occur outside of the framework of an exchange). So when you buy a share of stock on the stock market, you are not buying it from the company, you are buying it from some other existing shareholder. Likewise, when you sell your shares, you do not sell them back to the company?rather you sell them to some other investor.

The first stock markets appeared in Europe in the 16th and 17th centuries, mainly in port cities or trading hubs such as Antwerp, Amsterdam, and London.10? These early stock exchanges, however, were more akin to bond exchanges as the small number of companies did not issue equity. In fact, most early corporations were considered semi-public organizations since they had to be chartered by their government in order to conduct business.

In the late 18th century, stock markets began appearing in America, notably the New York Stock Exchange (NYSE), which allowed for equity shares to trade. The honor of the first stock exchange in America goes to the Philadelphia Stock Exchange (PHLX), which still exists today.11? The NYSE was founded in 1792 with the signing of the Buttonwood Agreement by 24 New York City stockbrokers and merchants. Prior to this official incorporation, traders and brokers would meet unofficially under a buttonwood tree on Wall Street to buy and sell shares.12?

The advent of modern stock markets ushered in an age of regulation and professionalization that now ensures buyers and sellers of shares can trust that their transactions will go through at fair prices and within a reasonable period of time. Today, there are many stock exchanges in the U.S. and throughout the world, many of which are linked together electronically. This in turn means markets are more efficient and more liquid.

There also exists a number of loosely regulated over-the-counter exchanges, sometimes known as bulletin boards, that go by the acronym OTCBB. OTCBB shares tend to be more risky since they list companies that fail to meet the more strict listing criteria of bigger exchanges.13? For example, larger exchanges may require that a company has been in operation for a certain amount of time before being listed, and that it meets certain conditions regarding company value and profitability.14? In most developed countries, stock exchanges are self-regulatory organizations (SROs), non-governmental organizations that have the power to create and enforce industry regulations and standards.15? The priority for stock exchanges is to protect investors through the establishment of rules that promote ethics and equality. Examples of such SRO?s in the U.S. include individual stock exchanges, as well as the National Association of Securities Dealers (NASD) and the Financial Industry Regulatory Authority (FINRA).

How Share Prices Are Set?

The prices of shares on a stock market can be set in a number of ways, but most the most common way is through an auction process where buyers and sellers place bids and offers to buy or sell. A bid is the price at which somebody wishes to buy, and an offer (or ask) is the price at which somebody wishes to sell. When the bid and ask coincide, a trade is made.

The overall market is made up of millions of investors and traders, who may have differing ideas about the value of a specific stock and thus the price at which they are willing to buy or sell it. The thousands of transactions that occur as these investors and traders convert their intentions to actions by buying and/or selling a stock cause minute-by-minute gyrations in it over the course of a trading day. A stock exchange provides a platform where such trading can be easily conducted by matching buyers and sellers of stocks. For the average person to get access to these exchanges, they would need a stockbroker. This stockbroker acts as the middleman between the buyer and the seller. Getting a stockbroker is most commonly accomplished by creating an account with a well established retail broker.

Stock Market Supply and Demand

The stock market also offers a fascinating example of the laws of supply and demand at work in real time. For every stock transaction, there must be a buyer and a seller. Because of the immutable laws of supply and demand, if there are more buyers for a specific stock than there are sellers of it, the stock price will trend up. Conversely, if there are more sellers of the stock than buyers, the price will trend down.

The bid-ask or bid-offer spread?the difference between the bid price for a stock and its ask or offer price?represents the difference between the highest price that a buyer is willing to pay or bid for a stock and the lowest price at which a seller is offering the stock. A trade transaction occurs either when a buyer accepts the ask price or a seller takes the bid price. If buyers outnumber sellers, they may be willing to raise their bids in order to acquire the stock; sellers will, therefore, ask higher prices for it, ratcheting the price up. If sellers outnumber buyers, they may be willing to accept lower offers for the stock, while buyers will also lower their bids, effectively forcing the price down.

Matching Buyers to Sellers

Some stock markets rely on professional traders to maintain continuous bids and offers since a motivated buyer or seller may not find each other at any given moment. These are known as specialists or market makers. A two-sided market consists of the bid and the offer, and the spread is the difference in price between the bid and the offer. The more narrow the price spread and the larger size of the bids and offers (the amount of shares on each side), the greater the liquidity of the stock. Moreover, if there are many buyers and sellers at sequentially higher and lower prices, the market is said to have good depth. Stock markets of high quality generally tend to have small bid-ask spreads, high liquidity, and good depth. Likewise, individual stocks of high quality, large companies tend to have the same characteristics.

Matching buyers and sellers of stocks on an exchange was initially done manually, but it is now increasingly carried out through computerized trading systems. The manual method of trading was based on a system known as "open outcry," in which traders used verbal and hand signal communications to buy and sell large blocks of stocks in the "trading pit" or the floor of an exchange.

However, the open outcry system has been superseded by electronic trading systems at most exchanges.16? These systems can match buyers and sellers far more efficiently and rapidly than humans can, resulting in significant benefits such as lower trading costs and faster trade execution.

Benefits of Stock Exchange Listing

Until recently, the ultimate goal for an entrepreneur was to get his or her company listed on a reputed stock exchange such as the New York Stock Exchange (NYSE) or Nasdaq, because of the obvious benefits, which include:

An exchange listing means ready liquidity for shares held by the company's shareholders.

It enables the company to raise additional funds by issuing more shares.

Having publicly traded shares makes it easier to set up stock options plans that are necessary to attract talented employees.

Listed companies have greater visibility in the marketplace; analyst coverage and demand from institutional investors can drive up the share price.

Listed shares can be used as currency by the company to make acquisitions in which part or all of the consideration is paid in stock.

These benefits mean that most large companies are public rather than private; very large private companies such as food and agriculture giant Cargill, industrial conglomerate Koch Industries, and DIY furniture retailer Ikea are among the world's most valuable private companies, and they are the exception rather than the norm.

Problems of Stock Exchange Listing

But there are some drawbacks to being listed on a stock exchange, such as:

Significant costs associated with listing on an exchange, such as listing fees and higher costs associated with compliance and reporting.

Burdensome regulations, which may constrict a company's ability to do business.

The short-term focus of most investors, which forces companies to try and beat their quarterly earnings estimates rather than taking a long-term approach to their corporate strategy.

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