The man who was once the world’s youngest billionaire now says he’s solved the stock market. Here’s his astonishingly simple portfolio.

The man who was once the world’s youngest billionaire now says he’s solved the stock market. Here’s his astonishingly simple portfolio.Listen(3 min)Listen(3 min)As portfolios go, the one put forward by John Arnold, the billionaire energy trader turned philanthropist, doesn’t get simpler.In a post on the social media service X, Arnold showed that a portfolio equal-weighted to the technology XLK and energy XLE sectors not only has posted double-digit returns in six of the last seven years, but produced positive returns when adjusted for risk. A Sharpe ratio measures an investment’s return per unit of risk, so any number above 1 is considered good, and he calculates his portfolio had a ratio of 1.16.About the AuthorSteven Goldstein is based in London and responsible for MarketWatch's coverage of financial markets in Europe, with a particular focus on global macro and commodities. Previously, he was Washington bureau chief, directing MarketWatch's economic, political and regulatory coverage. Follow Steve on Twitter: @MKTWgoldstein.A Dow Jones CompanyCopyright © 2026 MarketWatch, Inc. All rights reserved.