This year has given investors plenty of reasons to feel uneasy: The war in Iran, tariffs disrupting global trade and growing unease about the impact of artificial intelligence. In moments like these, it can feel as if investors need to do something, anything, to protect their nest egg. But that reaction can make a tough situation worse.

“The biggest mistake investors make is assuming they need to react to every headline,” says Julian Morris, a financial planner in Boston. “A well-built plan is designed to handle uncertainty, not follow the news cycle.” Recent history has shown the value of staying the course. The tariff-driven market sell-off in 2025 and the…