Anthropic’s COBOL Tool Rattled IBM, But AI Migration Still Hides Silent Bugs – Startup Fortune

AI coding agents can now translate decades-old COBOL into Java that compiles cleanly and passes its tests, then silently corrupt a database in production because they miss dependencies buried in old copybooks. Anthropic’s push into COBOL modernization rattled IBM’s stock in February 2026, and Gartner now predicts most mainframe exit projects will fail this year from overestimating what the AI can actually do.