(36)CCPs should only accept highly liquid collateral with minimal credit and market risk. In order to ensure that the collateral held by CCPs remains highly liquid at all times, it is necessary that CCPs establish transparent and predictable policies and procedures to assess and continuously monitor the liquidity of assets accepted as collateral, implement adequate valuation methodologies. To that purpose, CCPs should also implement concentration limits aimed at maintaining a sufficient diversification of the collateral to ensure that it can be liquidated promptly without significant market risk affecting its value. In determining their policies on eligible collateral and concentration limits they should take in account the global availability of such collateral in view of the potential macroeconomic effects of their policies.