Effective Spread

The Effective Spread is a measure of the actual cost of trading, calculated as twice the difference between the trade execution price and the midpoint of the best bid and offer. It provides a more accurate picture of transaction costs than the simple quoted bid-ask spread, as it accounts for the actual prices at which trades occur.

The effective spread reflects both the explicit costs of the spread and the implicit costs of slippage and market impact. It is a critical metric for institutional traders to evaluate the quality of their execution and the performance of their brokers.

By minimizing the effective spread, traders can significantly improve their long-term profitability. It is a standard benchmark in quantitative finance for assessing the efficiency of order execution across different venues.