The Digester

IBM shares tumble after Anthropic highlights AI for rewriting COBOL

Feb 24th 2026

Anthropic said its Claude Code tools can speed refactoring of COBOL systems, and investors pushed IBM stock down about 13 percent despite IBM already selling AI mainframe conversion tools.

  • Anthropic published that Claude Code can accelerate refactoring of COBOL and help document technical debt before migration.
  • IBM shares fell about 13 percent on the market reaction to the post.
  • IBM already offers AI-assisted mainframe code conversion, including watsonx Code Assistant for Z, and reported its highest mainframe revenue in 20 years last month.
  • Major vendors including AWS, Microsoft, Kyndryl and NTT have active mainframe migration initiatives.
  • Broader investor fears that AI could disrupt SaaS business models likely amplified the market reaction to the Anthropic post.

Sources

theregister.com