11th September 2026
Twenty-five years ago today, the world watched in disbelief as four passenger aircraft were hijacked and used in the attacks on the World Trade Center, the Pentagon and Pennsylvania. Nearly 3,000 people were killed.
The human consequences have lasted for a quarter of a century and will never disappear. But there was another immediate fear in those first days: what would happen to the world's economy?
The attacks struck at the heart of global commerce. The World Trade Center was not simply a collection of office buildings. It was part of the financial infrastructure through which money, commodities and international business moved around the world.
For a few days, it appeared that international commerce itself might be seriously disrupted.
And yet something remarkable happened. Trade adapted remarkably quickly. The United States closed its airspace after the attacks. Civilian aviation was effectively grounded and international flights were diverted. Normal air services began returning within days, although aviation took considerably longer to recover fully.
The disruption to air transport was severe. Passenger traffic fell sharply and the US airline industry entered a prolonged period of financial difficulty. But the world's wider trading system did not collapse.
The stock market provided an extraordinary illustration of the immediate shock. The New York Stock Exchange did not reopen until September 17, six days after the attacks. When it did, the Dow Jones Industrial Average fell 7.1%, one of the largest one-day falls it had experienced. By the end of that week the Dow had lost about 14%.
Yet the financial system continued functioning. The Federal Reserve moved rapidly to provide liquidity to banks, recognising that a financial panic could potentially turn the physical attack into a much larger economic crisis.
That response mattered. Banks still needed to make payments. Companies still needed to pay employees. Importers still needed to pay exporters. Businesses still needed access to credit.
The machinery of commerce had to keep running even though part of its physical infrastructure in New York had been destroyed. International trade also demonstrated something that is easy to overlook.
Trade is not one system with one switch. If a particular port, airport, financial centre or transport route is disrupted, businesses look for alternatives. Cargo can be redirected. Suppliers can be changed. Payments can be rerouted. Ships can wait. Trucks can take different routes. Companies can use different airports and ports.
That flexibility helped prevent the attacks from turning into a worldwide breakdown in the movement of goods. But 9/11 did permanently change the way international trade operated.
Before the attacks, the emphasis at many borders was largely on collecting taxes and checking whether goods were legal. Afterwards, security became a much more important part of international commerce.
The US introduced programmes such as the Customs-Trade Partnership Against Terrorism, while faster processing was offered to companies able to demonstrate that their supply chains met enhanced security requirements.
At the US-Mexico border, for example, the result was not the end of trade but the creation of a more security-conscious trading system. Twenty-five years later, trade experts describe that transformation as one of the lasting legacies of 9/11.
This is perhaps the most interesting lesson from the anniversary. The attacks changed how trade was conducted far more than they changed whether trade continued. There were more inspections. More documentation. More screening. More intelligence sharing. More security requirements.
And, eventually, much greater use of electronic information to establish where cargo had come from and who was responsible for it.
There was a cost. Security adds expense and time. Businesses have to comply with additional regulations and governments have to maintain increasingly sophisticated systems. But international commerce adapted. Indeed, the globalisation of trade continued at extraordinary speed during the years that followed.
China joined the World Trade Organization in December 2001, just three months after the attacks. Its entry helped accelerate the integration of China into the global trading system, with Chinese exports subsequently expanding dramatically.
That is an interesting historical coincidence. At the very moment that terrorism was making governments think about securing international trade, globalisation was continuing to expand.
Factories moved. Supply chains stretched across continents. Container shipping grew. Companies increasingly relied on components produced thousands of miles from where the finished product was assembled. The world economy therefore became simultaneously more security-conscious and more interconnected.
And that brings us back to the present. The world has experienced several enormous shocks since 2001.
The financial crisis. The Covid pandemic. The war in Ukraine. The disruption of shipping through the Red Sea. The tensions between the United States and China. And now the disruption surrounding the Strait of Hormuz and the surge in energy prices.
The difference today is that governments and businesses have discovered just how dependent modern economies have become on a relatively small number of critical routes and suppliers.
9/11 demonstrated that trade could survive a sudden shock. Covid demonstrated that global supply chains could become severely strained when factories closed and transport systems were disrupted simultaneously.
The Ukraine war demonstrated the vulnerability of energy and food supplies. The current Middle East crisis is demonstrating the importance of a single maritime passage through which a huge proportion of the world's energy supplies normally moves.
There is therefore a bigger lesson in the 9/11 anniversary than simply remembering how the financial markets reacted in September 2001.
Modern trade is remarkably resilient, but resilience does not mean invulnerability. After 9/11, much of the world economy began moving again surprisingly quickly because the underlying trading system remained intact.
That may not always be the case. If several critical shipping routes were disrupted simultaneously, or if a major conflict involved countries that dominate manufacturing, energy or semiconductor production, finding alternative suppliers would be much more difficult.
And that is why governments today are talking increasingly about resilience rather than simply efficiency. For decades businesses were encouraged to find the cheapest supplier, the cheapest transport route and the lowest inventory costs.
That produced enormous benefits for consumers. It also produced enormous dependencies.
The lesson of 9/11 was that international trade could absorb a huge shock. The lesson of the years since then may be that we should not assume every future shock will be so easily absorbed.
Perhaps the most remarkable thing about the aftermath of 9/11 was how quickly the world's commercial machinery began moving again.
The tragedy changed security. It changed aviation. It changed financial regulation. It changed international politics. But it did not stop globalisation.
In fact, global trade expanded enormously afterwards. That resilience is one of the great achievements of the modern trading system. It is also something we perhaps take for granted.
And as today's oil and shipping disruptions remind us, the next great test may not come from an attack on a financial centre.
It may come from the closing of a narrow stretch of sea thousands of miles away.