Comment by WorldMaker

A fancy term of art for all this is "cost-basis accounting". Your (double entry) account tracks only the cost basis (how much you have spent and when you spent it for what commodity) not the current price. Current price fluctuates with the market and you can track the price as well to build an unrealized gain/loss statement. This sort of statement is not an account, it's a report on an account. (And yeah, "unrealized" means what it says that it isn't real money in your accounts, just money you potentially could make if you sold/converted/traded what was in your accounts.)