OpenAI vs. Anthropic: GPT-5.5 Cyber Infiltrates 9 UK Banks, Regulators Concerned
2026-06-02
Bittime - OpenAI and Anthropic are engaged in a fierce competition in the cybersecurity sector. After Anthropic blocked UK banks' access to its AI cybersecurity tool, Claude Mythos, OpenAI quickly offered GPT-5.5 Cyber to nine major UK banks.
The nine banks that now have access to OpenAI GPT-5.5 Cyber include Lloyds Banking Group, HSBC, and Nationwide. NatWest and Santander already had access under previous agreements.
Key Points
OpenAI GPT-5.5 Cyber enters 9 UK banks– Replaces Claude Mythos who was blocked by Anthropic for the UK bank.
Regulators are concerned– The Governor of the Bank of England, the Chancellor of the Exchequer and central bankers are concerned that AI could weaken the security of the financial system.
Equal performance– The AI Security Institute rated both tools as achieving similar levels of performance in testing.
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Claude Mythos Blocked, OpenAI Enters
Anthropic announced Claude Mythos in April 2026. The tool claims to be able to find security vulnerabilities in digital systems, including one in a legacy system that had been hidden for nearly 30 years.
The myth has caused serious concern among finance ministers, central bankers, and regulators. They fear this model could undermine the security of the entire global financial system.
Bank of England chief Andrew Bailey warned last week that UK banks were still unable to access Mythos to test the security of their digital systems.
OpenAI responded quickly. George Osborne, the former British Chancellor and now a senior OpenAI executive, offered access to GPT-5.5 Cyber.
Osborne said OpenAI doesn't want to "hide this tool or keep it to ourselves," but acknowledged that, like Mythos, it won't be available to everyone.
"The important thing with these tools is that they have to be in the hands of the right people," he said.
"We want to ensure that the forces that enforce order in a democratic country have these tools, and that the forces that want to disrupt or commit crimes do not have them."
Read also:Claude vs ChatGPT vs Gemini: Advantages, Disadvantages, and How to Use Claude AI
AI Security Tool: Equal Performance
The AI Security Institute has tested Anthropic's Mythos and OpenAI's GPT-5.5 Cyber. In its report, the institute stated that both tools achieved "similar levels of performance" on the assigned tasks.
Prof Alan Woodward, a cybersecurity expert from the University of Surrey, explained: "I don't expect these tools to find anything that a human wouldn't eventually find, but they are relentless and meticulous in sorting through the millions of lines of code that exist in banking apps alone."
"In the UK, some of the code that the banking system still runs is very old, and AI would be very useful in finding problems there."
"They can do weeks of work in minutes — but they also produce false positives, so you still need humans in the loop to check their findings."
Read also:Claude's Data Leak: Anthropic Expresses Suspicions About Chinese Company
Why is Anthropic Blocking the Bank of England?
According to Anthropic representatives, the company is working hard to expand access to Mythos.
They believe that Mythos' capabilities are at a higher level than GPT-5.5 Cyber and therefore require more caution.
Anthropic initially opened Mythos to 42 companies, mostly other US tech firms.
Meanwhile, OpenAI has been more generous with access to GPT-5.5 Cyber, opening it up in the European Union and also to banks in Japan and Canada.
Both companies charge for use, although Anthropic provided $100 million for a Mythos preview.
Read also:What is Claude AI: How to Use It, Its Advantages, and How It's Different from ChatGPT
AI Competition Heats Up
Beyond cybersecurity, the OpenAI vs. Anthropic rivalry is intensifying. Anthropic is reportedly preparing for a major IPO.
The company just closed a $65 billion funding round at a total valuation of $900 billion.
OpenAI is also rumored to have IPO ambitions on a similar scale. Rumors about GPT-5.6 are also gaining steam, with claims of a context window capacity of up to 1.5 million tokens.
Meanwhile, Elon Musk, through SpaceX (which now incorporates xAI), is also planning an IPO in mid-June with a valuation of up to $1.8 trillion.
Read also:How to Get ChatGPT Plus for Free (Legal) in 2026
Conclusion
OpenAI GPT-5.5 Cyber is officially used by 9 major UK banks after Anthropic blocked Claude Mythos.
Regulators, including the Governor of the Bank of England, are concerned that these powerful AI cybersecurity tools could undermine the global financial system.
According to the AI Security Institute, both companies' AI security tools perform equally well. However, Anthropic is more cautious with Mythos's access, while OpenAI is more aggressive in expanding its reach.
UK banks' AI now has an alternative. The OpenAI vs. Anthropic rivalry isn't just about generative models, but also about who controls the world's most powerful cybersecurity tools.
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FAQ
What is OpenAI GPT-5.5 Cyber?
An AI cybersecurity tool designed to find security vulnerabilities in digital systems. It can outperform humans in hacking and cybersecurity tasks.
Which banks have access to GPT-5.5 Cyber?
Lloyds Banking Group, HSBC, Nationwide, NatWest, and Santander already have access.
Why did Anthropic block the British bank from Claude Mythos?
Anthropic believes Mythos' capabilities are more advanced and require greater caution. They are working to expand access.
What are regulators' concerns about AI cybersecurity?
Finance ministers and central bankers worry that AI tools could undermine the security of the entire global financial system.
Is GPT-5.5 Cyber better than Claude Mythos?
The AI Security Institute rated both as achieving similar levels of performance in testing.
Disclaimer: The views expressed belong exclusively to the author and do not reflect the views of this platform. This platform and its affiliates disclaim any responsibility for the accuracy or suitability of the information provided. It is for informational purposes only and not intended as financial or investment advice.
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