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WFN QUICK BRIEF · UNDER 1 MIN
The short version
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What the primary record establishes
US Rule 605 covers execution reports for specified orders in NMS stocks. Effective spread compares the execution with the appropriate midpoint of the national best bid and offer. For a purchase, double execution price minus midpoint. Reverse the subtraction for a sale. SEC staff FAQ on Rule 605 ↗
What the distinction changes
Suppose the bid is $19.98 and the offer $20.02. A buy fills 100 shares at $20.01 and 300 at $20.02. The individual effective spreads are two and four cents. Weighted by executed shares they average 3.5 cents.
What to check before drawing a conclusion
Compare similar order and size categories, and pair the spread with fill rates and execution speed. Reproducing the statistic requires the relevant quote at the proper time and records of each fill. The SEC staff FAQ provides examples for partial fills.
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Original WFN vector illustrationWFN · 6 November 2026
Editorial noteSource-based explanation with original WFN analysis. Historical records retain their dates; numerical examples are illustrative. The original vector illustration is conceptual and is not documentary evidence.
WFN REALITY LEDGER
What is on the record?
Primary-source explainer
Primary-source explainer
Primary record / reference periodSEC staff FAQ on Rule 605
The linked source supports the documented record; WFN interpretation and illustrative examples are separate.
01 · VERIFIED RECORD
What the primary record establishes
US Rule 605 covers execution reports for specified orders in NMS stocks. Effective spread compares the execution with the appropriate midpoint of the national best bid and offer. For a purchase, double execution price minus midpoint. Reverse the subtraction for a sale. SEC staff FAQ on Rule 605 ↗
02 · WFN EDITORIAL ANALYSIS
What the distinction changes
Suppose the bid is $19.98 and the offer $20.02. A buy fills 100 shares at $20.01 and 300 at $20.02. The individual effective spreads are two and four cents. Weighted by executed shares they average 3.5 cents.
03 · REVIEW POINTS
What to check before drawing a conclusion
Compare similar order and size categories, and pair the spread with fill rates and execution speed. Reproducing the statistic requires the relevant quote at the proper time and records of each fill. The SEC staff FAQ provides examples for partial fills.
