Most individual stocks are 'losers' — so why does the market keep rising?

Here's a fact that upends the stock-picker's dream: most individual stocks are bad investments. In a landmark study, Do Stocks Outperform Treasury Bills?, finance professor Hendrik Bessembinder examined nearly every U.S. common stock from 1926 to 2016. He found that 58% of them failed to beat one-month Treasury bills — the closest thing to a risk-free, do-nothing return — over their entire lifetimes. More than half of stocks actually delivered a negative lifetime return.

So how did the market create trillions in wealth? The answer is skew: a tiny handful of massive winners carried everything. The best-performing 4% of listed companies accounted for the entire net wealth gain of the U.S. stock market above T-bills. The other 96%, collectively, roughly canceled out. A few Apples and Amazons don't just beat the average — they are the average's whole story.

This is why diversification isn't a hedge for the timid — it's a mathematical necessity. If gains come from a rare few stocks you can't reliably identify in advance, then owning a small basket makes it likely you'll miss them entirely. Buying the whole haystack (via a broad index fund) guarantees you hold the needles. Concentrated stock-picking, by contrast, gives you great odds of underperforming a boring T-bill.