Is the US Stock Market in a Bubble?

The S&P 500's figure is currently 17. In spring 2017, it was just below 20. Three years back it was 18, and five years ago it was 14. Rather than describing a bubble, the forward P/E ratio appears to indicate "market as usual".

However, these forward P/E levels are not new. From the 2008 stock-market crash through 2015, forward P/E ratios were consistently lower than today's, but not that much lower, averaging about 14. Surely the difference between 17 and 14 does not constitute a bubble. What's more, the S&P 500's forward P/E ratio was 18 in 2003, and nobody calls that year a bubble, given that stocks were recovering from losses.

Forward P/E ratios are one way to judge stock prices. Other approaches could yield different conclusions. By selecting the measures that support bears’ cases – as I did myself when choosing forward P/E ratios – you can raise concerns about current stock prices. But they would be hard-pressed to demonstrate a bubble.

Some Tech Companies May Justify Valuations

I don't see a bubble – certainly not with the overall US stock market. At a time when 10-year Treasuries pay 3% and annual inflation hovers around 1%-3%, stocks are not dear when compared with the alternatives. At some point, of course, the economy will turn; those P/E ratios will spike because earnings collapse; and stocks will get it hard. But the same could have been written in 2012, and 2013, and so forth. Without further evidence, why believe this year is different?

With global technology stocks, the bubble claims may be on firmer ground. It is indeed true that the leading companies must grow their businesses dramatically to justify their stock prices. Sometimes, such minor miracles occur.

For 15 years, sceptics argued that Apple's (AAPL) and Amazon.com's (AMZN) share prices have assumed unrealistically strong business fundamentals. So far, so wrong. Often, though, a glamorous company's business fundamentals don't match the expectations. Perhaps now is that moment for the giant tech leaders.

But the thing is, real bubbles aren't modified by the word "perhaps". In my 30 years at Morningstar, I have encountered only two true bubbles in the stock and bond markets: speculation that led to what I regarded as obviously inflated security prices, accompanied by what appeared to outsiders as a mob mentality among buyers. One was Japanese stocks in the 1980s; the other, US tech firms in the late 1990s. Even at the time, I felt that doom was inevitable.

Not so with today's leading tech companies. They are expensive, certainly. That said, those companies have real, dominant businesses. It is possible, if not necessarily probable, that their business growth will match the sky-high expectations and they will continue to outperform other stocks. Even if that doesn't happen, there is a good chance that their returns will be positive.

Many bubbles are proclaimed, but few arrive. The word is not useful; rather than signal something extraordinary, it has come to mean "securities I don't like because they strike me as being too expensive".