Yes, the party will have to sell collateral, being what ever securities they are in, equities, bonds, gold, fixed interest.
But the combined total CSD outstanding on a security can be upto 15 - 100 times the face value of that security (greed).
The markets have priced in that the Greek debt will be resolved, I don't think they have priced in failure.
I have heard that the CSD in regards to Greece isn't large but neither is the countries debt ~$360 billion, compared to Spains and Italy's of over $1.2 Trillion. But look at the problems it is causing.
It is the contagion effect, because Portuguese debt will catch the cold very quickly.
You just have to visit this www site http://www.usdebtclock.org and see the currency and credit derivatives value.
value $780 trillion almost a Quadrillion, this is why USA interest rates can't go up or there will be another Depression, so I believe there won't be a QE3 unless it hits the fan in Europe?
If I was a Greek I would be buying gold, but hang on they're in debt with no savings.