IBM Suffers Worst Fall Since 2000

IBM shares posted their worst day in more than 25 years after AI startup Anthropic PBC said its Claude Code tool can help modernize Cobol, a legacy programming language that runs on IBM computers, Ryan Vlastelica and Brody Ford reported for Bloomberg News.

IBM defended its prospects, saying its core mainframe business provides the same performance and security across multiple programming languages, not just Cobol. (Photo: IBM)

The stock plunged 13%, marking its biggest single-day percentage loss since October 2000. With the decline, IBM shares have fallen 27% in February, putting the stock on track for its largest one-month drop since at least 1968, according to Bloomberg data.

“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 its prospects, saying its core mainframe business provides the same performance and security across multiple programming languages, not just Cobol.

“The value IBM mainframe delivers has nothing to do with Cobol,” IBM Senior Vice President Rob Thomas wrote in a blog post Monday.

“Whether the application is written in Cobol, Java, or any other language, the platform provides the same guarantees. The language is not the source of that value. The platform is.”