counterparty
From Longman Business Dictionarycounterpartycoun‧ter‧par‧ty /ˈkaʊntəpɑːti-tərpɑːrti/ noun (plural counterparties) [countable]FINANCE the person or company who you are buying from or selling to, when you buy or sell something such as a bondIn traditional trading, each side of the trade must assume that the counterparty will make good on its obligation. → central counterparty