Is that really the definition of a bubble though? A bubble implies irrational valuations. Trying to value a company as if they are the next Google is the purpo

Is that really the definition of a bubble though? A bubble implies irrational valuations. Trying to value a company as if they are the next Google is the purpose of the stock market and can be perfectly rational. Google sets a standard, and by its success, it demonstrates what other similar companies could do, which gives investors more confidence in upstarts like Facebook, which then leads to higher valuations. The state of our economy also leads to higher valuations - as money is worth less today than it was when Google went public, and there are fewer productive places for investors to put their money than when Google went public. At times when valuations become increasingly irrational you could say we are approaching a bubble, but this article's author did not offer a rational argument to back up his points.