One constant principle of investing is that markets fluctuate. Stock prices will rise and fall for a number of reasons: the economy, investor sentiment, political uncertainty at home or abroad, energy or weather problems, or even corporate scandals. This means market performance isn’t always predictable. That is why diversification, or spreading the investments in your portfolio among different asset classes and across different sectors within each class, is such an important strategy. Diversification is a time-tested way to manage risk.
The use of borrowed money “levers” or exaggerates the result of price movement. Suppose the stock moves to $200 a share and you sell it. If you had used your own money exclusively, your return would be 100% on your investment [($20,000 -$10,000)/$10,000]. If you had borrowed $5,000 to buy the stock and sold at $200 per share, your return would be 300 % [(20,000-$5,000)/$5,000] after repaying the $5,000 loan and excluding the cost of interest paid to the broker.
To make comparisons between companies, sectors and markets a little easier, there are a number of mathematical models used. The most common and often the most helpful is the P/E ratio. The Price to Earnings ratio takes the share price and is divided by the earnings per share. It is possible to calculate this using past earnings, projected future earnings and with all sorts of moving averages ;-) Therefore, this is one number that it is vital for any investor to know and understand.
3. Get an education. Warren Buffett has suggested in the past that every investor should be able to understand basic accountancy principles, an annual report and stock market history. You probably do not need to become an accountant, but being able to understand the scoring system of the game can only help. There are thousands of books about investing and trading - you don't need to read them all, but you probably ought to read a few to enhance your theoretical knowledge.
You’ll come across an overwhelming amount of information as you screen potential business partners. But it’s easier to home in on the right stuff when wearing a “business buyer” hat. You want to know how this company operates, its place in the overall industry, its competitors, its long-term prospects and whether it brings something new to the portfolio of businesses you already own.