What is pound-cost ravaging, and why does it matter at retirement?
Pound-cost ravaging is pound-cost averaging run backwards. Taking a fixed amount out of a falling portfolio means selling more units at each lower price, and those units are gone permanently — so when the market recovers, it recovers a smaller portfolio than the one that fell.
- The mechanism: a fixed withdrawal sells more units as prices fall.
- The permanence: sold units do not participate in the recovery.
- Where it bites: the first five to ten years of withdrawals, not later ones.
- The defences: a cash buffer, a variable withdrawal, or a guaranteed income floor.
01 The arithmetic
Consider £2,000 withdrawn monthly. At a unit price of £10 that sells 200 units; at £6 it sells 333. The falling market forces you to liquidate more of the portfolio to produce the same cash, and the extra units sold are permanently outside the recovery.
During accumulation the same price movement works in your favour: a fixed monthly contribution buys more units when prices fall, which is pound-cost averaging. Retirement inverts the mechanism entirely, and the intuition built over thirty years of saving becomes actively misleading.
The consequence is that a portfolio can fail even when average returns are perfectly adequate. What matters is the order, not the average, and the same set of annual returns rearranged can leave one retiree comfortable and another out of money.
Shows: how many more units a fixed withdrawal sells after a market fall, and what that does to the portfolio's recovery. Ignores: dividends, charges, tax, and the size and duration of any actual market move.
On the defaults above, the worked example shows 1029 units. The same withdrawal sells 3429 units instead of 2400 — 1029 extra units that never participate in the recovery.
Source: Retirement income market data
02 Why the first years matter most
Early losses do lasting harm because the portfolio is at its largest and the withdrawals have the longest time to compound the damage. A 25% fall in year two of a thirty-year retirement is a fundamentally different event from the same fall in year twenty-five.
This is sequence risk seen from the withdrawal side, and it is the reason a safe withdrawal rate is so much lower than an expected return. The rate has to survive the worst opening decade the history contains, not the average one.
It also means the risk window is finite. A retiree who gets through the first decade without a severe drawdown is in a materially safer position than the starting arithmetic suggested.
Source: Inflation and price indices
03 What actually protects against it
Three defences work, and they are not alternatives so much as layers. A cash buffer of one to two years of withdrawals means a fall does not force sales at all — you spend the cash and refill it when markets recover. A variable withdrawal reduces the amount sold in a bad year, which directly reduces the number of units liquidated.
The third is a guaranteed income floor. Where the State Pension, a defined benefit pension or an annuity covers essential spending, the portfolio withdrawal becomes discretionary and can be paused entirely — which removes the mechanism rather than mitigating it.
What does not work is holding a more conservative portfolio permanently. That reduces the size of the falls and also the returns, and over a thirty-year retirement the drag usually costs more than the protection is worth.
Source: Plan your retirement income
Everything you learned during thirty years of saving is wrong on the day you start withdrawing, and this is the sharpest version of it. Falling markets were your friend while you were buying; they are the enemy once you are selling. The practical response is dull and effective: hold a couple of years of spending in cash so you are never forced to sell into a fall, and be willing to take less in a bad year. Neither requires any skill at predicting markets, which is the point.
FAQ
Is this the same as sequence risk?
It is the mechanism behind it. Sequence risk describes why the order of returns matters; pound-cost ravaging is the specific reason — a fixed withdrawal sells more units at lower prices, and those units are permanently outside the recovery.
Does holding more bonds solve it?
It reduces the size of falls and the expected return at the same time. Over a thirty-year retirement the return drag usually costs more than the protection is worth, which is why cash buffers and variable withdrawals are the more common answers.
When does the risk pass?
It concentrates in the first five to ten years of withdrawals, when the portfolio is largest and the damage has longest to compound. A retiree who avoids a severe early drawdown is in a materially safer position than the opening arithmetic suggested.
Sources
Regulator references
- Retirement income market data · Financial Conduct Authority · 2025What UK savers actually do at retirement, measured rather than assumed.Last verified: 2026-09-07
- Inflation and price indices · Office for National Statistics · 2025The published index this post's real-terms figures are deflated by.Last verified: 2026-09-07
- Plan your retirement income · GOV.UK · 2025The government's own sequence for turning pension pots into income.Last verified: 2026-09-07
Calculator unit tests · the assertions this page's worked example is checked against, and their last result
Changelog
- 2026-09-07 — initial publish (new format)
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Jordan Reeves
Founder of Talk Through Wealth. A software engineer for over a decade before turning to retirement planning, Jordan built the projection engine after watching family members get fragmented, country-by-country advice that never reconciled. He writes about retirement the way the engine computes it: month-by-month, lifetime-long, and skeptical of any rule of thumb that hasn't been run through the math.