Marking to market ensures the contract holder and the clearinghouse that sufficient funds will be available to cover any loss resulting from the change in price of the derivative instrument. Assurances such as this are necessary when you consider that the margin requirements are as low as 5% of the contracts face value. if everything runs smoothly. The clearinghouse should have a perfectly matched book, with losers paying winners on a daily basis from their margin accounts. As a result, counterparty credit risk in this market should be very low.