Three staff members of the Office of Financial Research of the US Department of Treasury have issued a report claiming that, over time, large clearing members tend to dominate at clearinghouses, increasing the exposure of clearinghouses to their largest members. To counter such risk, the authors argued that clearinghouses should factor a concentration charge into the margin requirements of clearing members. The authors also proposed that clearinghouses, (1) when conducting their annual test of their default management processes regarding the default of an individual member, should consider the action of other clearinghouses affected by the same member’s default; and (2) when conducting stress tests, to include among each stress scenario an accounting for the actions of other clearinghouses.