Looking at volatility, historically speaking
There has been a ton of talk in the markets about the lack of volatility lately. Bill over at NO DooDahs! put up an interesting study yesterday, that got me thinking that I should revisit some of my own volatility research from a while back to provide a different perspective.
Average True Range (ATR) is an indicator that technical analyst use to measure period to period volatility in the form of the range over which markets trade – basically meaning the high to the low (plus any opening gap if there was one). The advantage of ATR over measures that are based on closing prices is that period to period changes (closes) do not necessarily give the full picture. After all, I know I’ve seen plenty of times when markets have run up a lot and/or down a lot, but ended the day essentially flat.
When I wrote an introduction to ATR article for Trade2Win about a year ago, I introduced the idea of using a normalized version of the indicator to really make the best use of it. We would expect price ranges to vary with the current market price. By that I mean a 1% move on a market at 100 is 1, while a similar move on a market at 1000 is 10. Thus, we would expect ATR to be higher in general terms for a higher priced market. If, however, we normalize the ATR reading by taking it as a percentage of current price, we can evaluate volatility over time without having a bias imparted by changing prices.
Here’s an example:

What you see above is the monthly S&P 500 chart (from the futures using continuous contract prices). It goes all the way back to the mid-1980s. If you look very closely, you can make out the Crash of 1987. Below prices I have plotted normalized ATR and the standard ATR. Notice how flat and smooth the lower plot of standard ATR is. There is a tiny little blip in 1987, then flat, then a steady rise through the late 1990s and in to the early part of this decade. ATR rose, as one would expect, with prices. It then dropped when prices fell, though interestingly it has not come back as the index has moved back up toward the highs.
Now compare that to normalized ATR. The Crash is much more obviously presented because normalize ATR captures the relatively violence of that time. Notice also that normalized ATR didn’t peak out until later because it also caught the relatively volatility that occured during the stock market sell-off.
Now let’s zoom in an take a closer look with the weekly chart.

Here again, we can really see how volatile things were during the bear market of the early 2000s. After that, the volatility dried up completely. It has stayed low during the whole of the recovering going back to 2003/2004.
And we can even see the pattern in the daily chart.

Again, the spikes in ATR have all come thanks to stock market declines. Whenever the market has been trending higher, things have been pretty narrowly traded.
This is the sort of thing you will see in most markets. The declines are much sharper and more violent than the rises. It’s panic selling, really. Have you ever heard of panic buying? Traders don’t normally act that way.
What we see on the monthly chart above is one of the reasons I’ve been a stock market bull for quite a while now. The normalized ATR is down around where it was in the middle 1990s before the market really took off. Until the readings start getting much higher than that, I’m not going to have any real worries about the long-term direction of prices.
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4 people have left comments
Posted on February 11, 2007 at 9:32 am
Stochastics advice please – Forex Forum wrote :
[...] current volatility levels stand historically speaking. I’ll refer you to my recent blog post on Average True Range as an example of what I’m talking about. Indicators are just a way to provide a filter or [...]
Posted on February 11, 2007 at 2:31 pm
Bill aka NO DooDahs! wrote :
I’m a big fan of ATR as well, but decided to use the StDev instead just because of its wider use. Both are saying pretty much the same thing and are generally correlated.
The “low volatility” pundits typically run in two packs: those without a longer-term perspective and those out to scaremonger.
Nice analysis.
Posted on February 11, 2007 at 3:15 pm
John wrote :
While I use StdDev a lot myself, it does have the restriction of being based only on closing price, so it doesn’t take the full price range in to consideration. Not that it’s not useful, mind you.
As for ATR, the thing that really shows when looking at the normalized reading is the impact the withdrawl of retail traders/investors had after 1987, and again after the peak in 2000. People have long blamed the hedge funds, et al for market volatility, but clearly it’s the individual traders that really create volatility.
Posted on June 12, 2009 at 9:14 am
Rhody Trader» Retail Traders Flooding Into Forex, Again wrote :
[...] in this weekly EUR/USD chart, that low volatility went away in a hurry in 2007. (Red line shows Normalized Average True Range, a measure of period range volatilty – higher levels mean wider period [...]