Robinhood: System Design #

• Robinhood: System Design — structured design using the delivery framework: requirements, capacity, core entities, order state machine (FIX Protocol), smart order routing (NBBO/PFOF), market data pipeline (SIP/OPRA), risk engine (PDT rule, margin, TradingControl), options pricing (QuantLib Black-Scholes), T+1 settlement (DTCC/NSCC), and fractional shares. Grounded in QuickFIX/J, Zipline, and QuantLib source code.