Realized Spread

Realized spread differs from quoted spread by incorporating the timing and direction of the trade relative to the market midpoint. In insider-trading surveillance and quant scoring, realized spread serves as a key metric of execution quality and information leakage. A trader executing large positions or trading on material non-public information may exhibit systematically tighter realized spreads compared to the quoted spread, suggesting either superior execution skill or foreknowledge of price movements. This metric becomes particularly critical in detecting shadow trading or front-running activity, where an insider's order flow exhibits anomalously favorable pricing relative to the prevailing bid-ask spread at execution time.

In quantitative insider-scoring platforms, realized spread is decomposed into adverse selection and inventory cost components. The adverse selection component reflects the market maker's protection against informed trading, while the inventory cost component reflects holding risk. Abnormally low realized spreads preceding corporate announcements or significant price moves can signal insider activity and warrant automated escalation to compliance teams. Integration of realized spread data with transaction timestamps, order sizes, and venue routing patterns enhances the detection of coordinated trading schemes or information-based execution strategies.