(14)With regard to initial margin, the requirements of this Regulation are likely to have a measurable impact on market liquidity, as assets provided as collateral cannot be liquidated or otherwise reused for the duration of the non-centrally cleared OTC derivative contract. Such requirements represent a significant change in market practice and present certain operational and practical challenges that will need to be managed as the new requirements come into effect. Taking into account that the variation margin already covers realised fluctuations in the value of non-centrally cleared OTC derivatives contracts up to the point of default, it is considered proportionate to apply a threshold of EUR 8 billion in gross notional amounts of outstanding contracts to the application of the initial margin requirements. This threshold applies at the group level or, where the counterparty is not part of a group, at the level of the single entity. The aggregated gross notional amount of outstanding contracts should be used as an adequate reference given that it is an appropriate metric for measuring the size and complexity of a portfolio of non-centrally cleared OTC derivative contracts. It is also a reference that is easy to monitor and report. These thresholds are also in line with the BCBS-IOSCO framework for non-centrally cleared OTC derivative contracts and are therefore consistent with international standards.