What’s The Difference Between A Bull And A Bubble?


During 2013, stock markets in the United States and Europe generally delivered very attractive returns so it’s not all surprising that talk of market bubbles fills the air. After all, bubbles are not a new phenomenon and they’ve done some damage in the past.

In the 1800s Charles Mackay penned Memoirs of Extraordinary Popular Delusions and the Madness of Crowds. The book chronicled some of the earliest bubbles, including Holland’s Tulipmania of 1624 during which tulip bulbs were valued more highly than gold. He also describes the popularity of the South Seas Corporation whose shares traded higher and higher (on little more than word of mouth) until the stock crashed. More recently, we’ve experienced bubbles in stock markets, real estate, technology stocks, and other types of assets.

So, how do we tell the difference between a bull market and a bubble? According to The Economist, Nobel Laureate Robert Shiller of Yale University, “Describes a bubble as ‘a psycho-economic phenomenon. It’s like a mental illness. It is marked by excessive enthusiasm, participation of the news media, and feelings of regret among people who weren’t in the bubble.’ They are often enlarged by an expansion of credit.”

Shiller measures valuation levels using cyclically-adjusted price-to-earning ratios (CAPEs). According to Barron’s, the Shiller CAPE for the S&P 500 Index was at 21 in January of 2013. That was higher than its long-term average and lower than its recent trend so U.S. equities were somewhere between neutral and significantly over valued. Since January 2013, some U.S. stock markets have delivered returns in the double digits, pushing the Shiller CAPE toward 25. On the face of it, U.S. equities appear to be highly valued.

However, in early December, The Economist reported Shiller was “not yet ready to declare a bubble in American equities… There is nothing like the same excitement about shares that was seen in the late 1990s; net flows into mutual funds only just turned positive this year. Another measure of public indifference is CNBC, a television station that tracks the financial markets, suffered its lowest ratings since 2005 in the third quarter.”

So, is this a bubble or a bull market? The experts aren’t certain. Keep your eyes peeled for signs of irrational exuberance.