I just reread some materials about economic history and realized that the lessons from the Great Depression are still truly meaningful for today’s generation—especially as we track market cycles.

The Great Depression began with the stock market crash in October 1929—the day many people call Black Tuesday. At that time, speculation in the market had created valuations that were completely unrealistic. When investors lost confidence, stock prices plunged without end and created a devastating chain reaction. Millions of Americans—many of whom had borrowed to invest—lost all their savings in a single night.

But the market crash was only the first step. What was truly serious was when banks began failing one after another. People tried to withdraw their money at the same time, but the banks had no sufficient reserves. With no deposit insurance and no protective regulations, when a bank closed, the entire community lost the savings of a lifetime. Credit dried up, and the economy was paralyzed.

To make matters worse, governments in different countries adopted protectionist policies such as the Smoot-Hawley Act, hoping to protect domestic industries. But this only triggered retaliatory measures from abroad, causing global trade to fall sharply. And when consumer demand declined, businesses laid off workers, creating a vicious cycle that was hard to escape.

As a result, unemployment reached 25% in some countries, thousands of businesses went bankrupt, and homelessness surged. The Great Depression spread worldwide, affecting North America, Europe, and other regions. Economic instability even led to political changes— in some countries, it became fertile ground for extremism.

The road to recovery was long and full of twists and turns. President Franklin D. Roosevelt carried out the New Deal with public works projects, setting up agencies to supervise the banking sector and the stock market. Many countries also began building systems for unemployment insurance, pensions, and social welfare. But what truly helped the economy get restarted was World War II—governments made massive investments in production and infrastructure, creating jobs and stimulating demand.

Looking back, the Great Depression teaches us that the world economy can be easily shaken. The lessons from that period still influence how leaders handle today’s crises—from deposit insurance and securities regulation to social safety-net programs. Policymakers learned that governments need to intervene proactively to stabilize the economy, ensure the safety of banks, and provide a social safety net. These are valuable lessons that we are still applying to this day.