And a key metric for measuring market volatility -- the Chicago Board Options Exchange's Volatility Index(VIX) -- has been on a tear. During the past six weeks, it's spiked nearly 42%.
That's quite a move for the VIX, which currently trades around 18. While it still has a ways to go before signaling high levels of fear, the sharp rise suggests the volatility plaguing Wall Street is here to stay.
"We're moving into a new era of volatility," said Jamie Tyrrell, a VIX trader at Group One Trading. He says investors should brace themselves for a prolonged period where the S&P 500 and the Dow could have some big daily swings of 1% or more in any given week.
What's behind the churning? Central bankers. Investors have had the Fed, the European Central Bank and the Bank of Japan to thank for this year's big run-up.
Unprecedented levels of bond buying by the central banks have helped boost stocks, which are up roughly 15% this year, and until recently helped push interest rates to record lows.
Now investors worry that central banks could shift from being a friend to the market to a foe. Many analysts have compared central bank intervention to a drug that investors have become hooked on. They're starting to come to terms with what withdrawal might feel like.