Sources & Methodology
How we decide which sources to trust, what requires updating, and how educational calculations are presented.
Source hierarchy
For rules and market structure, we prefer primary sources. Typical sources include the U.S. Securities and Exchange Commission and Investor.gov, FINRA, exchange/operator documentation from NYSE, Nasdaq and Cboe, broker disclosures and original academic research.
What gets verified
Rules, dates, margin requirements, settlement practices, trading halt procedures and other update-sensitive claims should be checked against current official material. Basic mathematical examples are independently calculated. Strategy claims are presented cautiously unless supported by robust evidence.
Educational calculations
Calculators on this site use simplified formulas designed to teach relationships. They cannot model every fee, margin rule, tax consequence, partial fill, gap or execution outcome. The assumptions are shown on the relevant tool page so users can understand what the output does—and does not—represent.
Update policy
Financial-market rules change. When we learn that a material statement is outdated, we aim to correct the page and, when useful, explain the transition rather than silently preserving obsolete advice.