A Salon article says that Trump's

trade war of choice against China has turned a steadily rising Dow Jones average, through 2017, into an unstable sawtooth pattern with massive single-day declines that are now tempting a full-on 2008-style collapse.

Leaving aside the prediction-like final part, is there some quantitative way to assess if there has been more US stock market instability after 2017 than in the period before? (Obviously starting sometime after the Great Recession.)

  • 1
    You might look at FRED data. Visually it looks to me as if Fall/Autumn 2011 may have had more dramatic one day percentage changes than recent months
    – Henry
    Commented Oct 6, 2019 at 2:35

1 Answer 1


There are a number of ways to measure stock market volatility. One is VIX, a measurement of volatility in the S&P implied by index options. Looking at the VIX chart, it would seem more accurate to say it was unusually low for much of 2016 and 2017, is now rising, and is not anywhere near a historic high.

I suspect that other measurements, such as standard deviation of daily returns, might lead to a different result. I suggest if you are interested, you calculate yourself that from a table of S&P 500 returns.

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    Looking at that chart, it seems to somewhat support the claim in question. It remained steadily low "through 2017" and has risen since 2018 (the start of the trade war). On the other hand, you are right that it also seems that 2016/17 were unusually low years, and the current value is about the same as 2012 to 2015. But interpreting the chart seems like a difficult task, so it would be great if we had reliable sources attempting to interpret it for us.
    – tim
    Commented Oct 2, 2019 at 17:49
  • @tim I believe my FINRA Series 3 has expired. ;-) Commented Oct 2, 2019 at 17:50

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