This is my understanding and it could be wrong. If you buy and sell shares (or anything relating to capital gains) valued in anything other than U.S. Dollars, you should also be aware of the implications of exchange rate volatility when completing Schedule D. A gain in Pounds Sterling, for example, may be a loss in U.S. Dollars on Schedule D, due to exchange rate variances at time of purchase verses time of sale. The nasty side is a loss in Pounds Sterling may result in a profit (and therefore taxable capital gains) in U.S. Dollars on Schedule D, again, due to exchange rate variances in the opposite direction. A reasonable gain in Pounds Sterling could be a large gain in U.S. Dollars, and would be taxed accordingly. If you are looking to invest in Pounds Sterling for stability, this could be a small consideration and is obviously more critical for mid to long term investing.
I avoid anything to do with the markets, so if I’m wrong on this I hope Guya will correct me.