By Ryan Vlastelica
Publication Date: 2026-02-23 21:36:00
(Bloomberg) — International Business Machines Corp. shares had their worst day in more than 25 years on Monday, after AI startup Anthropic PBC said its Claude Code tool can help modernize Cobol, a dated programming language that’s run on IBM computers.
The stock plunged 13% in its biggest single-day percentage loss since October 2000. With the decline, IBM shares have fallen 27% in February, on track for its biggest one-month slide since at least 1968, according to data compiled by Bloomberg.
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“Modernizing a Cobol system once required armies of consultants spending years mapping workflows,” Anthropic wrote in a blog post. “Tools like Claude Code can automate the exploration and analysis phases that consume most of the effort in Cobol modernization.”
IBM defended the company’s prospects saying its core mainframe computer business offers a platform that provides the same quality of performance and security for various…
