Most of the world's companies are duds, stock picker says

Two years ago, Professor of Finance Hank Bessembinder stirred up the market with his study showing all the wealth created by U.S. stocks is the result of gains in a small group of companies. His update hasn't changed the situation.

In this article published July 17, 2019, on Bloomberg:

It is historically the norm in the U.S. and around the world that a few top-performing companies have great influence over how the market does overall. It’s the norm and I expect it to be the case in the future.

Hank Bessembinder, professor of finance and Francis J. and Mary B. Labriola Endowed Chair in Competitive Business