(5)The legal and supervisory arrangements of the USA relative to TBAs and applicable to CCPs qualified as covered clearing agencies should therefore be deemed equivalent to the Union rules, provided that the binding internal rules and procedures of a CCP that clears TBAs and applies for recognition meets certain requirements with respect to risk management. In particular, the CCP should calculate and collect initial margins on the basis of a three-day liquidation period with respect to TBAs, on a net basis. Moreover, the CCP should apply measures designed to limit pro-cyclicality that are equivalent in delivering stable and conservative margins to any of the three measures laid down in Article 28(1) of Delegated Regulation (EU) No 153/2013 with respect to TBAs.