EconAir

This primer is aimed at the long-term investor. But this does not mean that you should necessarily hold all of the stocks and funds in your portfolio for a long time. WHY STOCK PRICES GO UP The movement of a stock index such as the S&P 500 or an individual stock depends on two things: Earning per share (EPS) and changes in EPS. Stock price/earnings per share ratio (PE ratio) and changes in the PE ratio. If the PE ratio stays the same, an increase in EPS often leads to an increase in the stock price. The same is true of a stock index. Rising EPS combined with a rising PE ratio is often the reason why a stock goes up more than the average stock. Since 2009, the beginning of the stock market recovery from the last recession, most of the increase in stock prices has been due to the increase in earnings per share (EPS). Well, that was easy. Well, not really. The stock market is “forward-looking,” that is, it tries to anticipate change, especially cha...

Positive Externality You need to know three things about management and finance: 80/20 Rule Opportunity Cost Compound Growth 80/20 Rule (Also called Pareto’s Law) This idea says that a relatively small percent of actions account for a relatively large percent of outcomes. Find and concentrate your efforts on the important influences on your business. The percentages aren’t always 80/20. Some examples: 20% of your customers account for 80% of your sales. McDonald’s accidentally learned that 10% of its customers accounted for 60% of its daytime sales. And it was an identifiable group that they had never aimed its advertised at. 20% of your product line accounts for 80% of your sales and profits. Often, companies with a large product line with many variations find that 50% of their products account for over 90% of sales. An even smaller percent usually account for most of the profits. 20% of your SKUs account for 80% of your stockouts (and l...

A basic assumption in economics and business finance is that individuals are rational in the sense that they compare the cost and benefits of a decision. Generally, this means comparing the cost of investing or consuming today to the expected benefits in the future. Cost is usually the price of the product or investment; expected benefits are harder to figure. The rule is simple; if the expected benefits are greater than the cost, buy it. If not, don’t. Even if the cost is spread out into the future – a car paid for with a cash down payment and a car loan – it is relatively easy in theory to discount future costs along with expected benefits back to “present value” (today’s dollars) and do the comparison. One question that economics and finance doesn’t ask is: Does how you make a purchase or investment affect the buying decision? Does it matter if you pay cash or use a credit card? Theoretically, the answer is no. But recent neuroscience research indicates that the answer...