Your answer is in the second sentence... These contracts are tallied in notional values because no one really can say how much they are worth.
No, I don't think that's the answer.
We know the gross value. The notional value simply takes the gross value and multiplies it by some estimated value which represents the number of times the same dollar is passed along.
Seems to me the "gross" value and the percentage of that gross value that has been lost in value, is the real measure of our problem...not the much exaggerated $700 trillion.
Correct, but $700 trillion makes a much cooler headline. ;)