Hundreds of employees from dozens of financial institutions across London will scramble to deal with a host of simulated cyber-attacks today.
The "Waking Shark II" war games will see bank staff, regulators and government officials gather to play out how they would react to various attacks, such as a hit on stock exchange systems.
The simulation is designed to test market participants' ability to quickly and effectively respond to the attacks on various parts of their businesses and make sure that, for example, ATMs are stocked with cash. There will also be a heavy focus on how companies co-operate with other firms and regulators.
Cyber threats are rapidly making their way up the table of concerns for financial institutions. Many have been the target of DDoS attacks by groups such as Anonymous while the South Korean government has blamed its Northern neighbour of hitting bank Web sites.
Earlier this year Britain's financial institutions were told by the Bank of England that they must put concrete plans in place over the next few months to deal with the growing threat of cyber-attacks, the Bank of England has warned.
The first "Waking Shark" took place two years ago, simulating attacks during the London Olympics. In July the US held its own "Quantum Dawn 2" exercise, prompting industry trade body Sifma to call on politicians to bring in legislation to improve communication between the government and private firms.
Andrew Miller, COO, Corero Network Security, says: "I think one of the biggest benefits we will see from Operation Waking Shark is not necessarily about banks learning to defend against cyber-attacks, but learning to cooperate. I personally believe that there needs to be more information sharing within financial organisations on the latest threats and attacks they are facing so they can develop a knowledge pool on how to protect against them."