I've been in the US with a J1 visa for one year now (non-resident alien for tax purposes) and expect to stay here for two more years. IRS website says that only US-source income is taxable for nonresident aliens, but I wonder does it apply to foreign investments too? specifically, if I invest in gold in Forex** using one of the offshore brokers (which are mostly not regulated in the US) should I pay taxes in the US on the gains? If not taxable, would I still need to report the gains to IRS when I fill taxes?
** This allows me to invest with leverage, compared to, say, buying a gold ETF