Stocks, Mutual funds and Capital Gains

[Daniel]

Hello,

This is related to my earlier thread "trial balance" but I felt it 
deserved a new thread. The conclusion of that thread is that the trial 
balance failed because I deal in multiple currencies and currency 
fluctuations introduce incomes and expenses outside any transactions.

Now I'm thinking: But what about stocks, mutual funds and real estate?

Anything that you trade and experiences capital gains and loses (stocks, 
mutual funds, your house, currencies, precious metals), can throw the 
trial balance totally out of whack.

All of these things can fit under the umbrella of "capital gains/loses". 
Whether the unit is a house, a foreign bank account or a stock, it seems 
like you should deal with price fluctuations the same way.

So, now my question:  How do you deal with price fluctuations in other 
commodities? Can I do the same thing for currencies?

Thanks for the help.
Daniel.