The most recent auction of carbon dioxide CO2 emissions allowances in the major U.S. northeast regional trading hub reached near record-high prices, as the number of allowances available was reduced. The latest Regional Greenhouse Gas Initiative (RGGI) quarterly auction, held September 6, 2023, resulted in a clearing price of $13.85 per ton for CO2 emissions allowances, surpassing the previous quarter’s clearing price by 9% and nearing the record price, $13.90 per ton, set in March 2022. Allowance prices have been increasing since RGGI’s March 2023 auction as fewer allowances have been made available over time.