For many years, interbank-offered rates (IBORs) have set the benchmark rate for lending on an unsecured basis. By the end of 2021, countries (including the U.S.) plan to phase out IBOR and move to a new benchmark known as alternate reference rates (ARR). The International Valuation Standards Council (IVSC) has issued a Perspectives Paper—IBOR Transition: A Valuation Guide that outlines the key challenges that arise for valuation professionals from the termination of IBOR. The paper also summarizes the areas that can contribute to “valuation uncertainty” and thereby increase “valuation risk” in appraisals of financial instruments arising from the transition away from IBOR.