Suppose you are driving on a highway with three lanes going in your direction and you come upon a toll plaza with six toll booths. Three toll booths are straight ahead in the three lanes of traffic, and the three other booths are off to the right. Which lane should you choose (86) There are usually enough people searching for the shortest line so as to make all the lines about the same length. 　　The term profit in economics has a very precise meaning. Economists, however, often loosely refer to “good deals” or profitable ventures with no risk as profit opportunities. Using the term loosely, a profit opportunity exists at the toll booths in one line is shorter than the others. The general view of economics is that profit opportunities are rare. At any one time there are many people searching for such opportunities, and as a consequence few exist. 　　At major banks in big cities, you can buy foreign currencies. The prices of these currencies are determined in world money market. With dollars we can buy marks; with these marks we can buy francs; and with these francs we can buy back dollars. Can we make money on this transaction If this is possible, we say that there are profit opportunities in the market. There are in fact almost never any profit opportunities of this kind in foreign currency markets. (87) There are always individuals looking for such opportunities, and if any opportunity does arise it is quickly eliminated. 　　If, for example, the mark-franc price is too low with respect to the other prices, there is an immediate rush to buy marks and sell francs, not by ordinary citizens at bank windows, but by a few large currency traders in Tokyo, London, or Zurich who watch prices every minute. Such a rush drives up the mark-franc prices to the no-profit-opportunity point. Markets like this, where any profit opportunities are eliminated almost instantaneously are said to be efficient markets. 　　The common language way of expressing the efficient market hypothesis is “there’s no such thing as a free lunch”. How should one react when a stock broker calls up with a hot tip on the stock market With skepticism. (88) There are thousands of individuals each day looking for hot tips in the market, and if a particular tip about a stock is valid there will be an immediate rush to buy the stock, which will quickly drive its price up. By the time the tip gets to your broker and then to you, the profit opportunity that arose from the tip (assuming that there was one) is likely to have been eliminated. Similar arguments can be made for bond markets and commodity markets. They are many “expert” in these markets, who take quick advantage of any news that affects prices. This economist’s view that there are very limited profit opportunities around can, of course, be carried too far. There are clearly times when profit opportunities exist. (89) Someone has to be first to get the news, and some people have quicker insights than others. Nevertheless, news does get disseminated quickly, and there are thousands of people with quick insights. The general view that profit opportunities are rare is close to the mark.