An expensive handcrafted mechanical watch may tell time no more accurately than a cheap quartz model; but, because few people can afford one, buying it signals that the owner is rich. Similarly, investors flock to stocks that have appreciated, because they have “momentum.”
这些“违反规律”在其他方面也会出现。顾客常会因为价格上涨而认为一种商品价值更高。一个原因可能是家价值信号。昂贵的手工机械表并不比廉价的石英表走时准确；但是，由于鲜有人买得起手工机械表，因此它成了富裕的象征。类似地，投资者喜欢涨起来的股票，因为它们有“动能”。