Take care when you trade. Not all markets are created equal.

Stock markets are:
....organisations set up to bring together the buyers and sellers of stocks. They may be very large and sophisticated (like the London Stock Exchange - LSE - or the New York Stock Exchange - NYSE). Or very small and crude (like a group of traders meeting on a regular street corner in the financial centre of a developing economy). The ability to buy and sell stocks and shares almost instantly does not occur by magic, but because there is a market set up to do it.

Markets are a business like any other - the London Stock Exchange (LSE) is a quoted company (full name: London Stock Exchange Group plc). Like any business it needs high volume (so it encourages lots of trading) and trust in the product (so it provides regulation to prevent abuse).

Markets have rules
Every market has its own rules of business. The sophisticated markets have rules to encourage fair trading, prevent manipulation and provide a level playing field of information flow. The less sophisticated markets do not.

Each market decides what stocks can be traded. So just because you have shares does not necessarily mean you can find a market to trade them.

Shares/stocks as a generic class are often called 'equities'. But stock markets have expanded into trading other stuff (like bonds). So the particular bits of stock markets that trade equities are called 'Equity Markets'.

The London Stock Exchange
Unless you are a very sophisticated investor all the share you buy will be on the LSE. The LSE comprises a number of markets, the most important one being the Main Market. The list of securities traded on the Main Market is called the Official List. If a company is on this list it is said to be 'listed'.

The LSE also runs the Alternative Investment Market (AIM) and other smaller markets in derivatives and other securities.

Each of these markets has its own rules of business and is subject to regulation through the Financial Services Authority. These rules and regulations will determine both the rules of the game (what trading and communication practices are allowed and what are not) and the allowed behaviour of companies that are listed. Companies can be de-listed, either at their own request or by edict of the LSE. If a company in which you invest is de-listed you will have to find a buyer for yourself.

Lessons for the simple investor:

• Only buy shares listed on the Main Market. The reason for this is that the Main Market is more tightly regulated than the others, and you have better protection.
• Be aware that even market professionals can use the terms 'Stock Exchange' and 'stock market' loosely. Even the word 'listed', which has a precise meaning, can be misused. Don't assume that they are necessarily referring to the Main Market.
• Sometimes shares are transferred from the Main Market to AIM. No need to panic, AIM is a perfectly respectable market, but you should perhaps consider selling at a suitable time.
• If shares you own are de-listed you can no longer sell them. (Well, you can try writing to the company Secretary to see if he can help). This is a disaster for you. But take some comfort from the fact that shares that de-list without buying out the private shareholders are usually bust anyway. you win some, you lose some.