1. A CCP shall regularly review the models and parameters adopted to calculate its margin requirements, default fund contributions, collateral requirements and other risk control mechanisms. It shall subject the models to rigorous and frequent stress tests to assess their resilience in extreme but plausible market conditions and shall perform back tests to assess the reliability of the methodology adopted. The CCP shall obtain independent validation, shall inform the Bank of England of the results of the tests performed and shall obtain its validation in accordance with paragraphs 1a, 1d and 1e before adopting any significant change to the models and parameters.
1a. Where a CCP intends to adopt any significant change to the models and parameters referred to in paragraph 1, it shall apply to the Bank of England for validation of that change. The CCP shall enclose an independent validation of the intended change to its applications. The Bank of England shall confirm the receipt of the co
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