Having traded the mini's since the beginning of 1999, there are a few observations I have made about the "action" in this contract...First, there is something to be said about the fact that the big contract is definitely playing second fiddle to the mini's...This alone has changed the action to some extent as the market does not "hold" as much at one level as it used to...There appear to be less participants in the electronic markets willing to "defend" a territory for any significant amount of time...This only adds to the volatility caused by program trading, index arbing, pit arbing, etc, etc...
It has become a well publicized fact in recent months that program trading is accounting for nearly half of the volume in the index futures now...This adds a certain amount of "unpredictability" to the shortest time frames as programs can either come in and put in an artificial bid or offer for 1 minute, 5 minutes, 10 minutes, 30 minutes, etc ,etc...No one can predict the duration of these programs, nor the extent of the swings that will be generated by them...
Certainly, support and resistance still reign supreme...But it is the "in between", the way action osciallates between the critical S/R levels that has changed, imho...After trading this thing for a long enough time, you tend to pick up the "dance" of this market, and I would definitely say that aside from the increase in programs, the increase in electronic trading, all of this has changed one specific feature of these markets, namely the "velocity" of the market...