Thanks for the quick response. Little correction in your math: remaining shares in your example are 15, not 20. But that doesn't affect your question.

Yes, FIFO is what tax authority uses for capital gains back home, so that would be the way to go, IMO. I'd be happy for a little mobile app like Stockona to show unrealized gain for an existing portfolio. If you want to get fancy, track and display realized gain/loss separately. I wouldn't mingle them together. A good reason is, again, taxes. I pay capital gains tax on realized gain, not on unrealized.