Most people probably never heard of Hendrik Bessembinder. He is a professor with Arizona State University. He specialized in financial market design. He went through a database of US companies two years ago, and published a paper in 2018 (Do stocks outperform Treasury bills?). Followed with a another study for global companies which was published in 2019 (Do Global Stocks Outperform US Treasury Bills?).
Their findings show that about 60% of global companies did worse than one-month US Treasury notes. The number was greater in the initial study which focused solely on the US.
The global equity market as a whole created over $44 trillion in shareholder wealth between 1990 and 2018 and beat Treasury notes. However, it primarily relied on compounding returns from a just a handful of companies. Apple, Microsoft, Google, Amazon and Exxon accounted for more than 8% of global net wealth creation in the last 20 years. In the last 10 years, Apple, Microsoft, Google, Amazon and Facebook generated more than 13% of the global net wealth creation. In 2016, Microsoft, Apple and Amazon account for 10% of S&P 500 returns. This year, Microsoft, Apple, Amazon, Google and Facebook account for almost 30% of the S&P 500 returns. The same companies account for more than 50% of Nasdaq 100 gains. So the trend is accelerating.
This explains why the so called best wealth management companies with dozens of Ph.D. from the best schools struggle to keep up with the indexes. Or why on average active managed accounts do not beat passive accounts based on your run-of-the-mill indexes. The very topic of a paper by J.B. Heaton (Why Indexing Works - Applied Stochastic Models in Business and Industry 33 (6), 690-693.)