Every trading edge in this knowledge base is exercised under a licence. Rules decide who may trade what, with how much leverage, through which intermediary, with what disclosure, and who is liable when it goes wrong. They change, and when they change they move money between traders, brokers, market makers and exchanges. Some recent examples:
What the study covers
- 1Overview: the licence to trade
- 2The US regulatory map
- 3Order routing: Reg NMS, best execution and payment for order flow
- 4Short selling: Regulation SHO and its relatives
- 5Margin: Reg T, Rule 4210 and the end of the PDT rule
- 6Options: disclosure, account approval and position limits
- 7Market access, kill switches, circuit breakers and surveillance
- 8Dodd-Frank and the swaps market
- 9Managing other people's money, and the line between publishing and advising
- 10Europe and the UK
- 11India: SEBI and the world's largest options market by contracts
- 12Other Asia and the rest
- 13US crypto rules, 2025–26
- 14How to read a rule change
- 15Who gains and who pays from recent rule changes
- 16Key numbers
- 17Landmark cases and rule changes
- 18Pitfalls
- 19How an expert thinks about it
- 20Glossary
Companies in this study
- Citadel Securities
- Robinhood
- Charles Schwab and thinkorswim
- Interactive Brokers
- Virtu Financial
- Cboe Global Markets
- CME Group
- Options Clearing Corporation
- Knight Capital
- Archegos Capital
- Jane Street
- National Stock Exchange of India
- Zerodha
- Korea Exchange
- IG Group
- eToro
- Saxo Bank
- FXCM and the Franc Shock
- tastytrade
- Coinbase Derivatives
- BitMEX
- Eurex (Deutsche Börse). In other knowledge bases: Finance: sections for banks, CME and ICE as businesses and bank capital rules.