The model combines a broker-specific routing/payment-for-order-flow proxy per share and a price/spread drag measured in basis points of the trade amount. Lower-priced stocks receive a larger spread-drag adjustment because quoted spreads are often larger relative to price.

• Stocks and ETFs only; options, crypto, OTC, margin, shorting, securities lending, tax effects, and regulatory fees are not included.
• Assumes marketable retail orders. Limit orders, odd lots, volatility, and liquidity can change the result materially.