"Whether a particular instance is a bubble will never be objective; we will always have disagreement ex ante and even ex post. But to have content, the term bub

"Whether a particular instance is a bubble will never be objective; we will always have disagreement ex ante and even ex post. But to have content, the term bubble should indicate a price that no reasonable future outcome can jus- tify. I believe that tech stocks in early 2000 fit this description. I don’t think there were assumptions— short of them owning the GDP of the Earth—that justified their valuations. However, in the wake of 1999–2000 and 2007–2008 and with the prevalence of the use of the word “bubble” to describe these two instances, we have dumbed the word down and now use it too much. An asset or a security is often declared to be in a bubble when it is more accurate to describe it as “expensive” or possess- ing a “lower than normal expected return.” The descriptions “lower than normal expected return” and “bubble” are not the same thing." http://www.cfapubs.org/doi/pdf/10.2469/faj.v70.n1.2 http://www.cfapubs.org/doi/pdf/10.2469/faj.v70.n1.2