[compsciphd]

its not a huge problem to hold stocks. it's a problem to hold funds as I understand due to PFIC issues. But one could buy individual stocks without a problem (heck, while living in the USA I owned foreign stocks as my company's stock was a canadian company and I took advantage of their ESPP and it wasn't a real problem)

[Question50]

Yes, non-US pooled funds (e.g., ETFs, mutual funds, etc.) as well as most non-US pensions fall afoul of PFIC rules and their complex & expensive reporting requirements. This usually bites people with mandatory contributions, such as Australia's Superannuation.