The distinguishing feature of a tri-party repo is that a custodian bank or international clearing organization, the tri-party agent, acts as an intermediary between the two parties to the repo. The tri-party agent is responsible for the administration of the transaction, including collateral allocation, marking to market, and substitution of collateral. In the US, the two principal tri-party agents are The Bank of New York Mellon and JP Morgan Chase, whilst in Europe the principal tri-party agents are Euroclear and Clearstream with SIX offering services in the Swiss market. The size of the US tri-party repo market peaked in 2008 before the worst effects of the crisis at approximately $2.8 trillion and by mid-2010 was about $1.6 trillion.