iggy explains the dump of these days..., page-5

There are also tax complications in the US of owning 'real' foreign securities (i.e. foreign account reporting requirements) which means that holding just one foreign share is more hassle than its worth. Maybe Vraetorian can give us more insight.

I know from personal experience that when Aussie companies have moved to a foreign country, the 'hassle factor' is something I consider.