Yesterday's hot fund cools down

Picture the annual sports day at a school. In the 100-metre race, one boy sprints out of nowhere and wins by a mile. Everyone is amazed. The next year, families crowd to watch him, certain he will win again. But this time he comes third. He did not become slow - it is just that his first race was helped by a perfect day: good wind, fresh legs, a slow field. When conditions returned to normal, so did he. He drifted back toward the middle of the pack.

John Bogle saw the same thing happen to hot mutual funds, year after year. A fund tops the charts, magazines splash its name, money pours in. Then it cools off and slips back toward ordinary. Bogle gave this its plain name: reversion to the mean - strong runs tend to fade back toward average. The star of last year is very often not the star of next year.

This study is about resisting the strongest pull in all of investing: the urge to chase whatever just won. It feels obviously smart to buy last year's winner. The humble arithmetic, and a hundred years of fading stars, say it usually disappoints.

"The mean" just means the average - the ordinary middle. Most results, over time, get pulled toward that middle. When a fund does spectacularly well for a year or two, a big part of that is usually luck: it happened to be crowded into the exact companies or corner of the market that was hot right then. Luck does not repeat on command. So when the hot corner cools, the fund slides back down toward the average - it reverts to the mean.

The trap is the timing of the chase. You only hear about the winner after it has already had its great run. By the time it is famous and you buy in, its lucky streak is often ending. So you buy high, ride it down as it reverts to average, and feel cheated. You did not pick a bad fund - you picked a fund that had already spent its lucky run, right before the fade.

So the reading skill is this: past dazzling performance is a weak promise about the future, and often a warning that the easy part is over. When you feel the strong pull to buy whatever just topped the list, remember the sprinter - the record-breaking day is usually followed by an ordinary one.

illustrative Every year, Aarvi looks up the single best-performing fund of the past year and moves all her money into it, chasing the star. Aarohi ignores the charts completely and just holds a plain low-cost basket of the whole market, never switching. Both start with ₹8,00,000 and run for five years. Here is how a typical chase plays out, because each hot fund reverts to the mean soon after Aarvi arrives.

Read the last row. Aarvi worked hard, watched the charts, and kept jumping to the proven winner. Yet she ended below Aarohi, who did nothing but sit still. Each fund Aarvi chased had already had its lucky run; she bought near its peak and held it as it reverted to the mean. Worse, every switch cost her fees and sometimes tax.

Aarohi never once tried to find the hot hand. She just accepted the ordinary market average - and because she did not chase, she did not keep buying high and did not keep paying to switch. The plain average, held cheaply, beat the exciting chase. That is reversion to the mean quietly doing its work.

Not every strong run is pure luck. Some businesses and some managers really are better, and a genuinely superior one can stay above average for a long time. Reversion to the mean is a strong tendency, not an iron law that instantly drags every winner down. The hard part is telling durable skill from a lucky streak - and you usually cannot tell for certain until years have passed.

"It went up, so it must come down" is not a trading signal. Reversion says results drift toward the average over time; it does not tell you when, or that a high-flyer will fall tomorrow. People misuse it to sell winners too early or to catch falling knives, expecting a bounce that takes years to arrive, if ever. The idea explains a long-run pull, not a next-week move.

The mean itself can move. "Reverting to the average" assumes there is a stable average to revert to. Sometimes the whole market or a whole sector shifts to a new level and does not come back. A thing can look "too high" against yesterday's average while a new, higher normal is quietly forming. Do not assume the old middle is where everything must return.

Avoiding the chase does not mean avoiding all judgement. The lesson is to stop blindly buying last year's winner - not to switch off your brain entirely. A cheap, sensible plan still needs care about costs and diversification. Reversion to the mean warns against one specific mistake; it is not a complete strategy on its own.

An Indian reader meets this idea every time a "top-performing fund of the year" list appears, or an agent points to a fund's dazzling one-year chart. The star small-cap fund of last year is often near the bottom this year; the hot sector that everyone piled into cools off and the crowd that chased it late feels burned. Bogle's warning is to distrust the shine of a recent hot run, because a big part of it was the luck of being in the right corner at the right time - and luck reverts.

The practical habit is to look at long records, not one lucky year, and to be deeply suspicious of your own urge to switch into whatever just soared. Every switch in India can also cost you exit loads and capital-gains tax, which quietly makes the chase even more expensive. Bogle's humble default answer was to hold the whole market cheaply and stop chasing altogether - you may study that as one disciplined response to the fading-star problem.

What this idea cannot tell you is which hot funds are genuine skill and which are luck, or exactly when a high-flyer will fade - nobody can time that. It only warns you, firmly, that a spectacular recent run is a weak and often misleading promise, and that chasing it usually means arriving late and paying for the privilege.