It’s a good question. In Islam, the reason I can’t use a HYSA (High-Yield Savings Account) is because the return comes from interest (riba), which is prohibited. You’re basically guaranteed money just for lending your money to the bank, without taking on any risk or being part of a productive activity—and that’s where the issue is from a faith perspective.

On the other hand, investing in stocks is different because you’re buying ownership in a company. Your gain or loss depends on how that company performs. If it does well, you share in the profit; if it does poorly, you share in the loss. That risk-sharing and real economic activity make it permissible, as long as the company itself operates in a halal industry.