Here is what the Nasdaq has looked like over the last ten years:
It's practically gone up in a straight line. And this is despite the fact that growth in the underlying real economy has been moderate or even mediocre in that period.
People have fingered QE for the spectacular rise in stocks. All that money printing didn't go into the real economy, instead it inflated assets.
However, QE is starting to reverse. Starting in October 2017, the Federal Reserve started to unwind QE, essentially reducing the money supply.
However, the party still kind of went on as the ECB continued it's QE program (which is even bigger than the Fed's), and the Bank of Japan also continued it's QE program (which dwarfs both the Fed and ECB one).
In the last couple of months we have had two significant announcements from the ECB and Bank of Japan. The ECB says it's going to end it's QE in Dec 2018. Note it's not going to reverse it - it's just going to stop and hold. The Bank of Japan has also said it is slowing down it's QE.
What does that mean? It means that from December, the Fed tightening will no longer be offset by European and Japanese easing. At that point the effects of Fed tightening will become apparent.
We're already seeing distress in the emerging markets. This will surely spread to equity markets as well. Brace yourself for a tough 2019.