Real-time risk and margin control means every order is checked against limits before it reaches a venue, and every account's buying power reflects intraday activity rather than yesterday's close. Two forces are pushing firms there at once: SEC Rule 15c3-5 requires pre-trade controls that cannot be bypassed, and FINRA's newer margin interpretations assume firms can compute requirements intraday.
The guides below cover the rules and the system implications side by side — what has to be checked, how fast, and what breaks when margin is computed overnight in a market that trades all day.
5 in-depth guides covering the rules, the systems, and the trade-offs.
The platform components built for the workflows in this topic.
Financial and regulatory controls applied before order entry — credit and capital thresholds, erroneous order checks, restricted security screens — under the direct and exclusive control of the broker-dealer, with documented annual review of their effectiveness.
Overnight margin engines compute one requirement per account per day from settled positions. Intraday requirements need position, price, and activity data as it happens, plus a path to feed the result back into buying power before the next order is accepted.
The move is away from a fixed equity threshold toward intraday margin standards tied to actual risk. In practice, firms need account-level risk profiles and real-time buying power rather than a single static gate.
By retaining what each control evaluated, the parameter values in force at that moment, who changed them and when, and the resulting accept or reject decision. Rule 15c3-5 also expects a documented annual review, which is far easier when the evidence is queryable rather than reconstructed from logs.
Inline checks are measured in microseconds when limits, positions, and prices are held in memory on the order path. The latency problems firms report usually come from checks that call out to a separate service or database, not from the checks themselves.
