Return, risk and costs
Total return combines price change and distributions; getting closer to the investor outcome requires costs and a distinction between nominal and real return.
What you will learn
- Calculate simple gross and net total return.
- Separate price, dividends, costs and inflation.
- List risks the formula does not capture.
- Explain what diversification can and cannot do.
Concept
A reproducible identity
For one share, simple period total Return can be written as (ending price − starting price + the Dividend) / starting price. It measures history or a scenario, not a forecast.
Process
From gross to net
Commissions, venue charges, foreign exchange, bid-ask effects and tax may reduce the result. A Cost may be explicit; other effects, such as crossing the Spread, appear in the execution price.
Calculation
Nominal is not real
Inflation reduces purchasing power. An exact real-return approximation is (1 + net nominal return) / (1 + inflation) − 1; simple subtraction is only an approximation.
Risk
Risk does not fit one number
• Price can fall and a distribution can change or disappear. • Limited Liquidity can prevent execution at the expected price. • Diversification can reduce dependence on one issuer, but cannot eliminate losses or all market risk.
Worked example
Fictional example: Cauce Solar
Example facts
- Purchase: 20 shares at €50.
- Sale: 20 shares at €53.
- Dividend: €0.50 per share; total costs: €12; period inflation: 3%.
Walkthrough
1: Initial outlay: €1,000. Price gain: €60. Dividends: €10.
2: Gross return: 70 / 1,000 = 7%. Net nominal return: (70 − 12) / 1,000 = 5.8%.
3: Exact approximate real return: 1.058 / 1.03 − 1 = 2.72%. Taxes and FX are not included.
Conclusion
Each layer (costs, inflation and, once known, tax and FX) reduces what the investor keeps; a 7% gross figure does not describe their outcome.
Lesson scope
- Jurisdiction
- General concepts with identified ES/EU and US examples.
- Temporal scope
- Sources checked 2026-08-27; check for updates.
Official sources
- Rentabilidad de una acción (opens in a new window)
Comisión Nacional del Mercado de Valores · ES
- Checked:
- Informarse antes de tomar decisiones de inversión (opens in a new window)
Comisión Nacional del Mercado de Valores · ES
- Checked:
- Diversificar inversiones: la clave para reducir riesgos (opens in a new window)
Finanzas para Todos · ES
- Checked:
- Los 3 pasos para tomar decisiones de inversión