A year's rainfall does not arrive evenly. Much of it falls in a handful of heavy downpours, while most days bring a little drizzle or nothing at all. Leave the water butt covered on the wrong few days and it stays close to empty, however many dry days it was left open. A market's long-term gain behaves in a similar way. Most of it arrives on a small number of unusually strong trading days, scattered unevenly across decades, not as a steady drip.
That unevenness has a consequence. A portfolio out of the market for even a handful of those days ends up in a very different place decades later, holding the same investments the rest of the time. The S&P 500, an index tracking 500 of the largest American companies, shows how large that gap has been over the last twenty years.
Ten missed days sounds small against several thousand trading days in twenty years. The chart shows how large the difference still is. The natural response is to sidestep the worst days while staying in for the best ones. That requires knowing in advance which days are which, and historically the two have not stayed apart.
later
March 2020 shows the pattern at its most extreme, but the same clustering shows up across the whole twenty-year period above. Separating a market's worst days from its best ones, in advance and in practice, means making two correct calls instead of one: an exit, and a precisely timed return.
Far more money has been lost by investors preparing for corrections than lost in the corrections themselves.Peter Lynch
Capital only experiences the days a portfolio is already invested for. Money placed into the market during a weak stretch is exposed to whatever comes next, including any strong days that follow closely behind. Money not yet invested cannot be exposed to a day that has already happened by the time it arrives.
This is the mechanism behind the phrase "time in the market beats timing the market." It describes exposure, not prediction: time spent invested determines how many of the days above a portfolio was exposed to, and that exposure cannot be added back once a specific day has passed.
This is also why many long-term investors do something that feels wrong at the time: they keep investing through a fall, and some deliberately add more. If the strongest days tend to arrive close to the weakest, money added during a decline is already in place when the recovery comes. Lower prices also mean each pound buys more than it did before.
Simple on paper, hard in practice. Investing through a fall asks for three things at the moment they are hardest to find.
Believing the long-term case when the headlines say otherwise.
Adding money while prices fall means trusting a reason for owning an investment that you worked out in calmer times. That belief has to rest on evidence, not hope.
Following a plan instead of remaking it every day.
A fixed monthly contribution decides in advance what happens during a fall, so fear does not get a vote. An automatic payment does not panic.
Waiting for a reward that may take years to arrive.
Prices can keep falling after you invest, and a recovery can take months or years. The benefit of buying low only shows up if you can stay put long enough to see it.
This works very differently for a whole market than for a single company. A broad, diversified market has historically recovered from its falls, though sometimes only after a very long wait: Japan's main share index took more than three decades to regain its 1989 peak.
A single company is another matter. Its fall may reflect a business that has genuinely got worse, and adding more can deepen a loss rather than set up a recovery. Conviction is only a strength when it rests on the right thing.
The big money is not in the buying or selling, but in the waiting.Charlie Munger
A market's long-run gain concentrates in a small number of trading days, not a steady daily drip.
Most days contribute little on their own. A handful carry a disproportionate share of the multi-decade result.
The best trading days and the worst trading days have historically sat close together in time.
That overlap is what makes removing only the bad days from a portfolio, on purpose, difficult to do in practice.
Missing even a few of those days changes an outcome by more than the day count alone would suggest.
Each missed day leaves less for every later year to grow from, so the gap widens rather than staying fixed.
Capital only experiences the days it is already invested for, in either direction.
Waiting, even briefly, does not retroactively add back a strong day that has already happened, and it does not undo a weak one already underway.
Investing through weakness takes conviction, discipline and patience.
It has historically worked across broad markets over long periods. For a single company, a falling price can mean the business itself has changed.
In short: most of the market's gains arrive on a handful of days, and you only collect them by already being invested.
The best days tend to arrive close to the worst, often in the middle of a frightening fall. Step out to avoid the pain and you risk missing the recovery, and missing just a few of those days can more than halve a long-term result. Investing through the fall keeps you in place for them, but only with the conviction, discipline and patience to see it through.
So next time markets are falling sharply, you can ask: will my regular contributions keep going? Is what I own broad enough to recover, and can I afford to wait for it? Those questions won't tell you where the bottom is. They help make sure you are still invested on the days that matter most.