Page "Market timing" Paragraph 3

Some consider market timing to be sensible in certain situations, such as an apparent bubble.

However, because the economy is a complex system that contains many factors, even at times of significant market optimism or pessimism, it remains difficult, if not impossible, to pre-determine the local maximum or minimum of future prices with any precision ; a so-called bubble can last for many years before prices collapse.

Likewise, a crash can persist for extended periods ; stocks that appear to be " cheap " at a glance, can often become much cheaper afterwards, before then either rebounding at some time in the future or heading toward bankruptcy.