Nanex Research

Nanex ~ 14-Mar-2013 ~ Disrupting Markets

One way to measure whole-market intraday volatility is by summing the changes in the NBBO (National Best Bid/Offer) in all stocks. The animation below shows changes to the NBBO Spread each second in NMS Stocks over a 9 minute period around noon (ET) between October 2006 and March 13, 2013. Each second shows the number of NMS stocks with increasing NBBO spreads minus the number with decreasing spreads. The price scale (not shown) ranges from +1000 to -1000, the time scale ranges from 11:56 to 12:03 (e.g. the 56 indicates 11:56, the larger 12 indicates 12:00pm).

The line spikes higher when spreads widen in a large number of stocks, it spikes lower when spreads decrease in a large number of stocks. We chose this period of time (12pm Eastern Time) because it avoids news events and is often the quietest part of the trading day. Note: these volatility spikes occur at all times of the trading day.

Reg NMS was rolled out in the first quarter of 2007. There is a noticeable change starting late 2007/early 2008. As you can see, this measure of volatility is often unrelated to market conditions: it is mostly a function of market manipulation. The most likely sources are momentum ignition and exploratory trading strategies, both of which are manipulation techniques that tilt the odds in favor of the fastest traders. The High Frequency Traders.

When the red line spikes, it means spreads have suddenly widened and then contracted in a large number of stocks. Chart shows the same 9 minutes of time for each trading day (11:55 to 12:04) .

Nanex Research