Anthropic’s AI Learns COBOL, Triggers Sharp Drop in IBM Stock

• February 24, 2026

Shares of IBM experienced an unprecedented one-day drop following recent news involving Anthropic, a developer specializing in artificial intelligence systems. The catalyst for this market reaction was Anthropic’s announcement that it successfully trained its AI service, Claude Code, to upgrade and modernize code written in COBOL, a programming language predominantly used in legacy systems operated by IBM computers.

AI Tackles Legacy Code and Shakes Market Confidence

COBOL, a language dating back to the late 1950s, remains deeply embedded in the infrastructure of many financial institutions and government agencies, with IBM’s mainframes playing a key role in running this code worldwide. Anthropic’s development of Claude Code to handle COBOL modernization signals a significant advancement in automating the maintenance and updating of these aging codebases.

While the technological leap benefits organizations seeking to extend the lifespan and functionality of COBOL-based applications, investors appear to have reacted negatively. IBM’s stock saw a record-setting single-day decline—a strong indicator of concerns over the potential impact Anthropic’s AI tools could have on IBM’s business related to legacy systems and associated services.

This market development underscores the growing influence that AI-driven automation is having on traditional technology companies, particularly those involved with legacy infrastructure. Solutions like Claude Code suggest a shift towards more efficient and less costly approaches to managing older software, which could reshape segments of the tech industry that rely heavily on human expertise for maintenance and modernization.

The evolving landscape of AI-assisted software engineering highlights both opportunities and challenges as established corporations adapt to the accelerating pace of technological change. The recent market response reflects investor apprehension about how these innovations might disrupt long-standing revenue streams tied to legacy technologies.

As AI systems become increasingly capable of performing complex coding tasks, the technology sector may see further adjustments in valuation and strategic focus, especially among companies with significant exposure to entrenched computing platforms and programming languages.

Anthropic’s new AI model trained to modernize COBOL code has sparked a significant single-day decline in IBM’s stock prices.