HSBC: A Look at History Shows World Markets Are Close to the Bottom

Since 1988, the MSCI All Country World total return index has suffered a drop of more than
10 percent on 16 occasions, averaging a 20 percent decline over a span of 18 weeks.,

By comparison, this retreat has lasted for 14 weeks, during which time the index has given back 19 percent. Though timing the market is a tricky task indeed, Laidler points out that investors who manage to buy the trough can look forward to an average 12-month return of more than 20 percent:
Other factors such as elevated valuations and low earnings growth amplified the
pressure on global equities, effectively adding "fuel to the fire."

The S&P 500 has tumbled by at least 2 percent for three consecutive sessions as of Monday,
only the third time this has occurred in more than 50 years.