Nuke these cities with 50 megaton surface blasts:
- Hong Kong
- New York City
This list is based on the assumption that all of the world's economies are highly interconnected and that instant illiquidity in one market will have immediate and highly destructive effects across all markets.
Since the Internet will still be largely functional, the world will know very quickly what happened. Mass panic in many metropolitan areas will ensue as no one has any idea if the attacks were a one-time thing or just the first phase. Expect mass exodus' from metropolitan areas as hundreds of millions of people attempt to flee potential target areas. This is a humanitarian crises of unprecedented proportions. No disaster management agency on the planet can handle that kind of scale. Fights over food, shelter and supplies will quickly turn deadly.
Panic is what kills people. Panic is what will rip the world apart.
The fallout from these weapons will irradiate much of Europe. Assuming a uniform wind from the south west, radiation levels of at least 1 rad/hour will reach Berlin, Prague, Munich, Hamburg, Edinburgh, and Boston. These cities are effected based on very very simple wind patterns. The actual fallout paths may be more or less widespread.
Note that The Hague isn't directly hit but it is inside the thermal blast radius where 3rd degree burns happen to all exposed flesh. If the winds are right, fallout rates of 100 rads/hour will fall on Shezhen and Donguan. Macau is also in the thermal blast radius for 2nd degree burns.
All told, approximately 41 million people have died with an additional 26 million injured. This does not include fatalities or injuries sustained from fall out.
Anyone who cares to look at a simulation of this attack may refer to this NUKEMAP.
Depending on how the records are kept, the destruction of all these markets will mean that ownership of trillions of dollars of assets can't be guaranteed or quickly verified. Stock ownership is certified by physical certificates which may or may not be destroyed when the markets are. Uncertainly like this has a high likelihood of inducing panic in investors who will want to get cash as quickly as possible. However, the markets are the only place to convert an asset to cash but the markets don't exist anymore. All across the world, investors who get news of the attacks will have no way of knowing when or where the next attacks will happen. They will try to convert whatever assets they have to cash since cash is the most flexible asset to use in emergencies. Some, perhaps many, people will keep their heads and not sell off all their assets but enough people will panic that it causes market crashes everywhere. "Circuit breaker" mechanisms in the surviving markets will halt trading to prevent the markets from crashing further.
Even though the Chinese and Japanese markets are still functioning, the local traders are well aware that their economic livelihoods depends greatly on the US economy which is now in tatters. The value of exports from Chinese and Japanese companies will decrease considerably because of the increased uncertainty concerning future demand. Without demand for products, factory managers everywhere will reduce the hours or outright lay-off many workers. The reduction in spending power of all these workers will hurt the local economies, further deepening the growing recession.
In these attacks, the offices of many companies will be destroyed, along with the people who run those offices. As of 2005, 602 headquarters operated from New York City. 40 of the Fortune 500 companies are headquartered in NYC. A company can survive the loss of its entire C-suite executives but it will take months to regroup and restart operations. Paris hosts the headquarters of 33 Fortune Global 500 companies. All those companies will need to find new headquarters or somehow restore HQ operations rapidly.
Destroying New York will remove approximately \$1.33 trillion dollars or 7% from the US economy. This is equivalent to the loss in GDP from the Great Recession except it's a permanent loss. London's economy is \$546 billion dollars or 18% of the UK economy. Paris' economy is \$792 billion dollars or ~27% of the French economy. This list could go on but you get the idea. The destruction of the global market cities not only instantaneously destroys significant fractions of each country's economy but it also removes that countries capacity to rebound quickly because of the loss of highly educated workers. New York, London, Paris and Zurich, and presumably all global financial centers have services-based economies. All companies outside the attack areas who previously relied on services provided in the destroyed areas must bring those services back in-house or must do without. This has profound effects on corporate profitability in many industries.
In the case of Amsterdam, Paris, London, Dublin, and Seoul the center of government for the respective country has been destroyed. All of those countries will have greatly reduced ability to recover from the attacks.
Humanity will eventually recover but it will take decades.