Hi, I'm currently comparing index options in the US and in my own Dutch FTA exchange. Some background: for a few years now I traded the dutch (Amsterdam) FTA.EOE index options. I first did this through a Dutch broker but it became to costly and clunky and I switched to IB. Because I'm used to my home market I decided to go on trading them for a while and maybe switch to US options later, a possibility that wasn't available earlier. So, also due to other (technical) reasons I'm now contemplating a switch. I started looking for the option chains and compared them to what I already have. Two things struck me and I want to know if I'm correct. 1) margin requirements are much higher in the US. Selling an SPX ATM feb07 put demands about 18.000 margin (as indicated by 'check margin' in TWS). An ATM feb07 put on the EOE index needs about 3500 in margin. Of course the SPX has 3 times the worth of the EOE (1430 against 505) but has a lower IV (10% against 12%). Around 8.000 would be comparable. 2) The spread. The same ATM puts, the SPX one trades 13.40 (51) against 14.50 (18), a spread of 1,10 or 8%. The EOE put trades for 7.15 to 7.30, spread of 0,15 or 2%. Am I missing something here, or maybe looking at the wrong ladders? There are many different structures available so that is very well possible. Are there better (index) options to trade on the US exchanges, or should I keep trading my own turf? I can see liquidity in the US is better but not with the expected result of closing b/a spreads. Also, the higher margin requirements would make it hard to get a reasonable ROI trading (short) options. Are my numbers correct, and if so, how do we explain this remarkable difference? Any light on this issue would be welcome. Ursa..