A measure of the effective interest rate prevailing in the euro overnight market, calculated (up to 30 September 2019) as a weighted average of the interest rates on unsecured interbank overnight lending transactions denominated in euro, as reported by a panel of banks; and (from 2 October 2019 until its discontinuation on 3 January 2022) as the €STR plus a fixed spread of 8.5 basis points, with the €STR reflecting the trading activity of the previous TARGET2 business day.