Prior to the GFC, clearinghouses were one of many players in the interest rate derivative (IRD) market. The main action was between banks, as they could set bespoke terms for whatever they needed, and normally did not use initial margin. Clearinghouse trades tend to be at set terms and required initial margin, making them both less convenient and more expensive. This made them the counterparty of last resort. However, after the GFC, regulators have forced back to move more and more IRD trades to central clearing. This has greatly simplified the IRD market.
