Mixed collateral triparty repo trades play an important role in the funding activity of many market participants. Under General Collateral Financing, market participants will agree to a trade without specifying the exact collateral they will accept from a broader bucket of high quality, liquid assets, which include US Treasurys, TIPS, and Agency MBS. Under these trades, it is not unusual for agency general collateral repo trades to be topped off with Treasury securities if the dealer does not have sufficient Agency MBS to complete the deal.
The SEC understands that market participants may use US Treasury securities as permissible substitutions for other types of collateral and generally should not consider mixed CUSIP triparty repos resulting from such a permissible substitution as within the scope of the definition of an eligible secondary market transaction. However, if a mixed CUSIP triparty repo is eligible to be cleared and contains US Treasury CUSIPS from the outset of a transaction, such a transaction would be included in the scope of the definition of an eligible secondary market transaction.