The FTSE 100 bull run has been underway for more than five years now, or more than 66 months exactly, making it the fourth longest bull run on record. The longest on record was the increase in stock prices from 1990 to 2000, ending in the dotcom bubble. That lasted for 117 months. Then there was the run from 1921 to 1929, which lasted 97 months, before the famous stock market crash on record. The rally after the second world war ran for 70 months from 1949 until 1956.