Whilst trading routinely involves decision making, there are no more important decisions you have to make than when to close positions. Quite a few traders often overlook this part of trading or underestimate how important that it is. It is selling that impacts directly on whether or not you make any money trading. Buying shares is simply a means of putting yourself in a position to make money from trading.

There is a typical experiment which is conducted in Economic and similar classes, which relates well to selling shares. It involves dividing a room of people into two groups. Everybody in the first group is handed an imaginary coffee mug. People in the second group receive nothing.

Everybody in the first group is asked to write down on a piece of paper how much they would be prepared to sell their coffee mug for. Everybody in the second group is asked to write down on a piece of paper how much they would be prepared to buy the coffee mug for.

The amounts from all people within each group are compiled and an average calculated for each group. Generally speaking the average amount from the owners of the coffee mugs is double that of the average amount from the potential buyers of the coffee mugs. This observation supports the Endowment Theory.

The Endowment Theory suggests that people who own something place a greater value on it than those who do not have it. This is applicable in the sharemarket, and can affect your decision making when deciding to sell shares that you should be selling. Often you will find yourself owning shares and believing that they are worth more than what the present share price is. The only unfortunate thing about that is the real price is what it is presently trading for on the market and not what you think they should be worth.

This can affect you by convincing you not to sell shares when you may be best advised to sell them to stop any further potential loss. You may have bought shares for $4.00 and set a stop loss at $3.50 for example. A week later the shares are trading at $3.50 and you have received your cue to sell them. Thoughts enter you mind about how it was only a week ago that you paid $4.00 for them and how you think they are still worth that especially when you consider the report they released last week concerning future growth, for example.

These thoughts can paralyse you to take no action and not cut your losses and consequently have you breaking one of the most important time tested rules you can follow.