Strategie
Portfolio Withdrawal Strategy: The 4% Rule and Its Real Risks
Key takeaways
- The 4% rule comes from the Trinity Study and states that a 4% annual withdrawal historically lasted in most 30-year scenarios.
- Sequence-of-returns risk is the biggest threat: a deep decline right at the start of the withdrawal phase devastates a portfolio even if the average return is good.
- Over longer horizons (40–50 years) a safer rate is around 3–3.5%.
- Inflation erodes the real value of withdrawals if they are not increased annually.
- The 4% rule is a starting point for planning, not a guarantee — complement it with spending flexibility.
The 4% rule is the best-known guideline for withdrawing income from an investment portfolio — it states that if you draw 4% of the portfolio's value annually, it historically survived most 30-year scenarios. But there is a vast difference between "historically survived" and "will always survive."
Where the rule comes from
The Trinity Study from 1998 (Cooley, Hubbard, Walz) analysed historical US market data from 1926 and tested various withdrawal rates and allocations. Result: a 4% withdrawal from a portfolio of 50–75% equities survived in approximately 95% of rolling 30-year periods. That is a solid number — but pay attention to the assumptions.
Sequence-of-returns risk: the enemy of every retiree
Sequence-of-returns risk is the biggest threat that many investors do not know about. The point is that the order of returns over time matters — not just the average. If a deep decline arrives in the first years of the withdrawal phase, you sell fund units cheaply in large quantities, thereby reducing the base for future returns. The mathematics then falls apart, even if the average portfolio return is fine.
Example: investor A and investor B have the same average annual returns over 20 years, but in reverse order. The investor who started withdrawing in a year of major decline can exhaust the portfolio 5–10 years earlier than the investor who experienced the same declines late.
Inflation: the silent erosion of income
4% of the portfolio has a certain purchasing power today. If you do not adjust for inflation, the real value of withdrawals will be substantially lower in 20 years. The Trinity Study calculated with inflation adjustments — but that means nominal withdrawals grow, which increases the pressure on the portfolio.
How to adapt the rule for real-life planning
- For a 40+ year horizon count on 3–3.5% as a safer rate.
- Maintain spending flexibility — draw less in a downturn year.
- Combine with other income: rent, state pension, dynamic withdrawal strategy.
- Hold a cash cushion covering 1–2 years of withdrawals so you do not have to sell in a downturn.
FAQ
What is the 4% rule?
It states that 4% can be withdrawn from a portfolio each year and the money historically lasted in most 30-year scenarios. It comes from the Trinity Study of 1998 and is the best-known guideline for planning income from investments.
What is sequence-of-returns risk?
Sequence-of-returns risk means that the order of returns over time matters. A deep decline at the start of the withdrawal phase is devastating — you sell fund units cheaply in large quantities and reduce the base for future returns. The same average return but a bad start equals a portfolio exhausted much sooner.
Is the 4% rule reliable for the Czech Republic and longer horizons?
Less so than for the US over 30 years. For longer horizons (40–50 years typical for FIRE) 3–3.5% is safer. For the Czech Republic long historical data are lacking. Treat the 4% rule as a starting point for planning, not a guarantee of outcome.