[blahedo]

The article says he actually gave it up last September, so the numbers might have been fuzzier then. Regardless, he's protected from tax on any subsequent rise in stock price. You can't escape past or current tax, but you can "escape" future taxation.

On the ten-year tax shadow: How would that even work? If you were no longer a citizen, what claim would the US have on your money?

[rada]

There is a rule - quite reasonable in my opinion - that if you were to renounce your US citizenship but then come back for more than 120 days (per year) during the first 10 years following your "resignation", you are considered a resident of the US for tax purposes. It is designed to deter Americans from giving up citizenship solely for tax evasion purposes, as opposed to actually moving to another country. I imagine one enforcement mechanism would be the denial of entry.