This Practice Note focuses on the regulatory framework for systematic internalisers (SIs) under the recast Markets in Financial Instruments Directive (Directive 2014/65/EU) (MiFID II), as amended by Directive (EU) 2024/790 (the MiFID II Review), and the Markets in Financial Instruments Regulation (Regulation (EU) 600/2014) (MiFIR), as amended by Regulation (EU) 2024/791 (the MiFIR Review), (together the MiFID II framework). For more information about trading venues under the MiFID II framework (regulated markets (RMs), multilateral trading facilities (MTFs) and organised trading facilities (OTFs), see Practice Note: MiFID II: EU trading venues. What are systematic internalisers and why are they regulated? Funds, insurance companies and other large-scale investors have two broad options for buying and selling securities. They can buy or sell on a trading venue in which multiple buyers and sellers interact with each other, or they can trade directly with an investment firm which will deal on its own account when settling its transactions with them. In this case the traded securities will be sourced from, or added to, the investment firm’s own holdings of securities or,