Only clearing members face the clearing-house directly. Everyone else — introducing brokers, prop firms, most funds and all retail — clears through one. Membership requires substantial capital and participation in the guaranty-fund.
The number of clearing members has shrunk steadily since 2008, which concentrates risk: a handful of large firms now clear most retail futures flow.
Example: when a customer default exceeds their margin, the clearing member covers the gap from its own capital before any mutualised fund is touched.
Related: clearing-house, guaranty-fund, fcm, novation, segregated-funds