ON AUGUST 22nd America’s bull market in equities turned 3,453 days old. Since hitting a low of 666 in March 2009, the S&P 500 index has increased more than fourfold, driven by strong corporate profits, low inflation, stable economic growth and a boatload of central-bank stimulus. Despite five corrections of at least 10%, the index has never entered bear territory, defined as a drop of at least 20%. Most commentators are declaring this to be the longest bull market in history.
Whether it is a record-breaker is disputed. Some contend that because a fall of 19.9% in 1990 did not quite reach the technical threshold, the bull market that ended in 2000 actually lasted a whopping 4,494 days and is the true champion. Others note a drop of 19%-plus in 2011 (and declines of 20%-plus in other share-price indices).

