Repo transaction (“Buy-back agreement”) refers to a so-called ‘sale and repurchase agreement’ (German: ‘Verträge zum Kauf und Rückkauf’) involving commodities or EU Allowances on credit. Under such an agreement, the borrower transfers the commodities or à EUAs as collateral to the lender. At the end of the term, the borrower undertakes to repurchase this collateral and to pay the interest agreed for the loan.