Fathom this out if you can.
Here is the average minute by minute volatility of EU in the past 6 months, using the A0 feed from Esginal. A0 is the name for their aggregate feed - a combination of around 100 or so brokers and MMs.
Why is there a markedly different volatility between odd and even minutes across the hour? Is this:
a) poor data from Esignal
b) some kind of fallout from HFT
c) because people prefer to trade on even minutes rather than odd ones (ok... maybe not)