The challenge is having a reciprocal regulatory agreement. Otherwise, you'll need to file an affidavit demonstrating you are a qualified individual, an institution or a B/D dealing with one of those. You can see the rules and affidavit on Eurex's website. Index stuff on the CFTC side is different and available to US retail - SEC-regulated requires RRA. If they're not available via Eurex you should check the foreign exchange's website. Qualified investors or institutions will find them available from almost every international bank and be aware they ain't cheap to trade. The obstacle - generally is the cost of providing the SEC the regulatory access and the cost. Generally, $100,000,000 account size, but the dealing banks can work for exceptions, but your still talking material account size.