It's Just the Order

Same returns, opposite endings

While you are still adding money, the order of your returns does not matter at all. A good decade followed by a bad one, or the bad one first — it makes no difference to where you land, because multiplication does not care about order: 1.2 × 0.8 is exactly 0.8 × 1.2. This is why the accumulation years feel forgiving. You can be unlucky early and the arithmetic forgives you completely.

The day you start spending, that forgiveness vanishes. Below are two retirees who get the exact same thirty annual returns — same set, same average, same everything — in opposite order. One meets the bad years early; the other meets them last. Each withdraws the same amount every year. Set the withdrawal, then flip spending off and watch the two endings snap together — proof that the gap is made entirely of the spending, not the returns.

The mechanism is brutally simple. When you sell to live during a crash, you turn a paper loss into a permanent one — those shares are gone and can never recover. Sell into an early crash and you spend the rest of your life compounding a smaller base; the same crash at the end lands on a fortune that has already done its growing. Identical returns, identical average, identical withdrawals — and yet one retiree dies rich and the other runs dry, decided by nothing but when the bad years happened to fall.

“The retiree who encounters a bear market in the first years of retirement is in far greater danger than one who meets it later — even if their average return is identical.”

The sequence-of-returns problem · after William Bengen

So the danger isn't your average return — you can't control that anyway, and both retirees here had the same one. The danger is being a forced seller at the wrong moment. Which raises the practical question: if you can't choose the order, how do you stop a bad early year from forcing your hand? Game Two is the cheapest answer there is.

Spend a little less when it's down

If ruin comes from selling too much into a downturn, the cheapest fix isn't a clever portfolio — it's a flexible one. Most retirees plan to spend the same amount every year, come what may. But the years that actually break a plan are the bad ones early on, and those are exactly the years you can afford to ease off a little: skip a trip, hold the line on the budget, don't take the inflation raise. A modest, temporary trim in the lean years gives the portfolio room to heal instead of bleeding it at the worst possible moment.

Below, the same retirement is simulated thousands of times over random markets. Spend the same withdraws a fixed amount every year, crash or boom. Trim in lean years cuts spending by a set amount whenever the portfolio is down on where it started — and restores it once the market recovers. Set the withdrawal rate and how much you're willing to trim, and watch how many retirements are still solvent at each year.

Notice what the flexibility is really buying: it's not return, and it's not a big sacrifice. The trim only bites in the bad years — when you'd want to be careful anyway — and most retirements never need it at all. Yet that small willingness to bend is worth more than almost any tweak to the portfolio, because it attacks the actual cause of ruin: spending hard into a falling market. A cash reserve of a couple of years' spending is one popular way to fund those leaner years without selling — but the protection comes from the smaller withdrawal, not from the cash itself.

Flexibility changes how you withdraw. But there is a blunter lever still — how much you withdraw — and it does not behave like a dial at all. Game Three is the one that should change what number you pick.

The withdrawal rate is a cliff, not a dial

It is tempting to treat the withdrawal rate as a slider you can nudge: take a little more, accept a little more risk, smoothly. It isn't. Because a portfolio under withdrawal lives or dies on whether it can outrun the spending, there is a band where the odds are gentle — and then a knee, where a single extra percent of spending stops being a small indulgence and becomes a sharp jump in the chance you outlive your money. The famous “4%” isn't a magic constant; it's roughly where, for a thirty-year horizon, the curve is still flat enough to feel safe.

Below, the same thousands of random retirements are run across a whole range of withdrawal rates. The curve is the chance of running out before the horizon. Drag your withdrawal rate and your horizon, and find the knee — the point where the line stops crawling and starts to climb.

This is why the right move is so rarely “just take a bit more.” In the flat zone, a smaller withdrawal buys an almost absurd amount of safety for very little forgone spending; past the knee, the same one percent you'd barely notice in your budget can be the difference between dying rich and running out at eighty. The number you pick matters far more than the fund you pick — and unlike the market, it's the one variable entirely in your hands.