There is nothing mysterious. Floor traders and firms holding seats on the exchange are the ones to decide. If tick size was 0.1 noone would use the pit, and all these people be out of job. Altogether different question is, who would win and who would lose if both ES and SP were 0.25 or both were 0.1. some people suggest scalpers would benefit, but I am not sure. It is important to keep some nonzero tick size, small enough to not be economically significant. This is so that people cannot jump in front by offering a tiny bit better price. There are rules in place which have to do with time-priority of limit orders, and these are very important.
I agree that it would be frustrating if you had been bid at 1230.00 for 2 hours and someone came in and bid at 1230.01 and got filled immediately. However, not allowing that flies in the face of a free market. Especially an electronic market.
It is even more frustrating to bid at best bid, trading some hundred contracts there, but you wont get shit becase you entered some seconds later than the bigger dudes, and seconds later it trades several ticks higher. I want the ability to place a bid at 1210.10 for example. Floor traders, you are allready dead, why dont you guys give up. Anyway - Price BEFORE time, always!
I agree Remiraz. That's what I've been saying. Considering that this is all electronic there is no reason that the tick increment can't be the smallest size that can be equated to a round monetary amount. ES is currnetly $50 per point which means that a point can be divided up 5000 times and that division would each be worth a penny. i.e. smallest tick is 0.0002 That does seem a bit small though. 0.01 tick size is 50 cents a tick.
Apparently half the ET traders don't think tick increment is important. Or the exorbitant CME fees for emini trading (vs pit). Or much excitement about the Russel2K product from EurexUS, with much lower costs and margins. Maybe it's a coincidence, but there hasn't been any daily P/L posts by futures traders in "Trader P/L" thread here in ET. I wonder why...
Actually there was a thread recently started from a guy complaining he couldn't make more than 0.50 a day on ES.