Anthropic Launches Claude Code to Accelerate COBOL Modernization, Rattling IBM Shares and Mainframe Business

Since its introduction in 1959, COBOL has underpinned critical systems at banks, airlines and government agencies. Anthropic says the language handles about 95% of U.S. ATM transactions. The high cost of switching has created a defensive moat around IBM’s mainframe and maintenance services. If Claude Code can automatically map dependencies and business logic, it could reduce the staffing needs and costs of multiyear modernization projects.

On February 23, 2026, Anthropic said Claude Code could automate COBOL discovery and analysis that previously took consulting teams years to complete. IBM shares plunged 13.2% that day to close at $223.35, their biggest one-day decline since October 18, 2000, wiping about $31.6 billion from the company’s market value. The stock’s cumulative decline in February reached 27%.