One of the most important trading Rules is Preserve Your Capital - it is the capital at your disposal that determines ultimately your capacities to invest in a variety of assets, properties like the real assets, equity stocks, bonds and bullion and many other types of financial and other assets. As such, it is natural that for a trader or investor in stock markets, preserving your capital is very important. You should be really wary of any step in the stock market which may reduce your capital, that is, your trading capital. When you have sufficient capital to sustain your requirements and activities in the stock markets, you will find that you have better and more trading opportunities. On the other hand, if you lack the capital sufficient for your requirements, then you can not enjoy the trading opportunities which may come across during the day or during a longer time frame of few days or weeks. Therefore, it is of paramount importance as a stock trader (or, even as a relatively long term investor) to ensure to avoid large erosion to your capital. It is natural in stock market trading and investing that your capital shall remain exposed to risk and may get eroded at sometimes - you should always be on guard to control all your investment risks to preserve your capital. Once you preserve your capital, the only possible way the capital may move is to register a growth: this way, you can continue to earn profits from your stock trading and similar activities of trading and investing.
In stock market related transactions, there is always the probability of losses. However, losses should not become debilitating and one should always be careful to preserve capital. If losses go beyond the manageable level, the capital base shall get eroded and the capacity to invest or trade shall get diminished. If it continues, there shall not be any capital left to trade!