The Globe and Mail reports in its Saturday edition that the stock market is going through an affordability crisis. The Globe's Ian McGugan writes that share prices in Canada and the United States have shot up in recent years and not always for the best reasons. What seems to be driving them, at least in part, is an outburst of inflated expectations. If stock prices were booming because earnings were surging, there would be a lot to cheer and little to worry about. All else being equal, a stock that doubled in value because its earnings doubled in size would be just as good a purchase as it was previously. But that is not exactly what is happening. Yes, earnings have grown at a nice clip. However, what has also expanded is how much investors are willing to pay for each dollar of those earnings. The benchmark S&P 500 Index of big U.S. companies sold for 16 times expected earnings in 2016. It now sells for 23 times earnings. In decades past, people were typically willing to pay a mid-teens multiple of earnings for a profitable, mature company with moderate growth expectations. Go back 10 years and even high-growth superstars such as Apple and Alphabet sold for under 23 times earnings. These days? The sky's the limit.