News Summary

• John Arnold, the billionaire energy trader-turned-philanthropist, made his fortune by predicting the direction of markets.
• Now, he’s sounding the alarm on fast-growing prediction markets, saying they’re harmful to young men and boys.
• His concern lies in how platforms for sports-event contracts and online betting more broadly are designed to keep users constantly engaged.
• Unlike traditional forms of gambling, wagers can be placed seamlessly — quickly and easily through mobile apps with direct links to bank accounts.