I thought US citizens are taxed on income (but not capital gains) even when outside the US? I had friends who had to file US income tax returns while living overseas
US citizens regardless of their residency are responsible to pay taxes on all global income and assets. Thus, if you live in the US, but have a brokerage account in Bermuda or Hongkong (where there are no local capital gains taxes) you are still required to pay US federal taxes on capital gains from your overseas brokerage account. The same would be true if you lived in Bermuda or Hongkong.