# Single Stock Skew

_Portfolio Theory . 2026-07-01 . By Tanmay Kurtkoti. Educational, illustrative, not advice._

A friend asked me last week for the one stock to buy and forget for the next ten years. Just tell me the name, he said. I pulled up a study I keep going back to, because the answer it gives is not the one anyone wants.

Hendrik Bessembinder went through every US stock in the record since 1926, about 25300 of them. Fifty seven percent, over their entire lifetimes, did worse than a one month Treasury bill. That is basically the risk free rate, the return you get for taking no equity risk at all. The median stock actually lost money. Not underperformed. Lost money.

So where did the famous long run return of the stock market come from? Four percent of the names. That sliver, about 1092 companies, created all of the net wealth, roughly 35 trillion dollars of it. The other 96 percent, added together across nine decades, just matched a Treasury bill. Ninety firms made over half. Five made a tenth.

Before anyone files this under American exceptionalism, the same team ran it on global stocks from 1990. Sixty one percent trailed a US T-bill. The same lopsided shape everywhere you look.

Here is what it does to the one stock question. If almost all the return lives in a handful of names, the odds that you, picking by hand, land on them are brutal. Which flips how I read diversification. It is not the timid choice. Owning a wide, whole market slice is the only reliable way to be sure the four percent that pay for everything are actually in your portfolio when they run.

You do not have to find the needle. You have to own enough of the haystack that you cannot miss it