Sure buying foreign securities is somewhat difficult for Americans but it is not illegal for them to buy them. Any American with a Vanguard or Fidelity international fund in their 401k likely has a few foreign securities. Hell, Vanguard even suggests that you hold at least 20% of your portfolio in foreign. You just have to find a domestic broker that has them or open up a brokerage account in the country that has them for sale. Sure there are rules and regulations and taxation like the ones mentioned above but other countries want rich American money. It is not as difficult as you may think to find brokers. If kraken plays their cards right they could be the only exchange in US territories that also functions as a brokerage.