The EU Emissions Trading System (ETS) is the largest and first carbon emissions trading system in the world. In 2020 this market accounted for 88% of total value of all carbon emission trading systems globally with 8 billion emission allowances changing hands, with a market value of €201bn . The legislation around the market is constantly evolving. The European Commission’s goal to become carbon neutral by 2050 and reduce greenhouse gas emissions by 55% from 1990 levels by 2030 has inspired the latest round of legislative changes that were announced in July 2021.