The EU’s comprehensive trading and conduct-of-business rulebook (effective 2018) covering investment firms, including FX trading. MiFID II/MiFIR introduced detailed compliance obligations: classifying clients (retail/professional/eligible); enforcing best execution; imposing transparency and transaction-reporting requirements; and adding specific rules for algorithmic trading. It also gave ESMA power to cap leverage and require other investor protections as noted above. The UK retained analogous rules in “UK MiFID.”