SOURCES: SEC Press Release 2020-321 · SEC/CRS IF12332 · SEC Order Competition Rule (Rule 615) & 2025 withdrawal · Reg NMS · FINRA Rule 5310 · EU MiFIR Art. 39a · FCA FG12/13 / COBS 2.3 · Robinhood FY2024 results. Scene 4 price ladder & market-share figures are illustrative / industry estimates.