Never before have so many of the most important countries in the world printed so much money & left base rates at near zero for so long.

http://www.businessinsider.com.au/deutsche-banks-jim-reid-sums-up-everything-thats-terrifying-about-the-markets-2015-9

Three sentences from Deutsche Bank’s Jim Reid nail the reason why markets are so terrifying

Global markets are going ballistic at the moment and if you’re trying to predict what might happen in the medium-term — then good luck.
Chinese and US stocks have experienced historically violent upswings and plunges in the past few months, while oil was hammered down 10% on Tuesday after climbing more than 25% in three days.
Analysts from Credit Suisse note that the declines have been more or less the same as the market turmoil after the 9/11 terrorist attacks.
Many may hope that there’s a precedent in history that can help navigate through turbulent trading at the moment.
Well, stop looking. We’re in unknown territory.
Deutsche Bank’s Jim Reid sums up how we got here as clearly as anyone can in three crisp sentences:

One of the biggest problems we face is that there is no historical template for current global market conditions so we’re all flying blind to a large degree. Never before have so many of the most important countries in the world printed so much money and left base rates at near zero for so long. Also never before has the largest economy in the world tried to start a slow process of reversing said extraordinary policy.