International Business Machines Corp. (IBM) sign on the floor of the New York Stock Exchange (NYSE) on Monday, December 8, 2025 in New York, USA.
Michael Nagle | Bloomberg | Getty Images
international business machine Anthropic’s stock price plummeted on Monday after the company announced that its Claude Code tools can be used to modernize legacy systems running COBOL, making it the latest casualty of rapidly evolving AI technology.
IBM’s stock price fell nearly 13.2% to close the day at $223.35 per share after Anthropic announced Monday that it could use Claude code to automate the exploration and analysis work that drives much of the complexity in modernizing COBOL, IBM’s core business. IBM has long sold mainframe systems optimized for large-scale transaction processing, often using COBOL.
COBOL, short for Common Business-Oriented Language, is a major code system developed in the late 1950s that is often used in business data processing such as payment processing and retail transaction systems. According to Anthropic, an estimated 95% of U.S. ATM transactions use COBOL, making it a prime target for cost-effective AI disruption.
“Hundreds of billions of lines of COBOL are executed every day in production environments, powering critical systems in finance, airlines, and government. Yet, the number of people who understand COBOL is decreasing every year,” Anthropic wrote in a blog post on Monday. “AI is great at streamlining tasks that used to make COBOL modernization too expensive.”
Claude Code helps modernize COBOL codebases by mapping dependencies across thousands of lines of code, documenting workflows, and identifying risks that “would take months for a human analyst to surface,” Anthropic said.
“Modernizing legacy code has been stagnant for years because understanding legacy code is more expensive than rewriting it. AI has turned that equation on its head,” the blog post said.
This latest use case builds on Anthropic’s efforts to disrupt legacy code systems and the company’s digital transformation efforts, which are bogged down by decreased developer productivity and “technical debt.” Technical debt refers to the future costs of shortcut solutions in software development, leading to increased maintenance for a company in the future.
IBM is the stock that has fallen the most on concerns about AI, which has spooked investors in recent weeks and is contributing to a volatile “sell first, ask questions later” trading environment. On Friday, a number of cybersecurity companies tumbled after Anthropic announced a new feature called Claude Code Security built into Claude Code. The new feature scans codebases for security vulnerabilities and can find vulnerabilities in software that can be reviewed by humans. The sector remained under pressure in Monday trading.
Monday’s plunge has pushed IBM stock down more than 24% since the beginning of the year.
