Average Return Is Not The Return You Keep

Friend waves his fund statement at me over coffee, thrilled.

Averaged 12 percent a year, he says, tapping the number the app prints right at the top. I asked him what he actually turned his money into. Long pause. And that pause is the whole story, because the average return a fund advertises and the return you compound are almost never the same figure.

Here is the cleanest way I know to see it. A fund goes up 50 percent one year, then down 50 percent the next. The simple average of those two years is zero, so it feels like you broke even. You did not. Rs 100 grew to 150, then halved to 75. You are down a quarter, on a fund whose average return was exactly nothing.

And it scales with the size of the ride. Up 10 then down 10 leaves you at 99. Up 30 then down 30 at 91. Up 50 then down 50 at 75. Every one of those averages zero. Not one climbs back to 100. The swing itself is a cost, and the bigger the swing the bigger the bite.

Give two funds the same positive average and the tax just runs quietly. A calm one earning 10 then 10 turns Rs 100 into 121. A choppy one that jumps 30 then gives back 10, the exact same 10 percent average, ends at 117. Same headline number. Stretch that across a couple of decades and the small gap is not four rupees, it is lakhs.

So when a statement shows you a big average, ask the next question. What did it actually compound to. The average is the brochure. The volatility is the bill. You do not beat it by watching harder, you beat it by holding steadier