TLDRs;
- IBM shares fell 13% after AI startup Anthropic unveiled Claude Code, sparking investor fears about legacy business risks.
- Anthropic’s Claude Code tool automates COBOL modernization, a process traditionally requiring extensive manual coding effort.
- The market fears AI automation tools could diminish IBM’s mainframe revenue and affect long-term growth prospects.
- IBM’s mainframe operations remain vital, serving financial institutions and governments relying on COBOL applications.
- IBM faces the dual challenge of adapting to AI trends while maintaining its legacy system revenue streams.
IBM (IBM) saw its stock tumble by as much as 13% on February 23, marking its most significant intraday decline since March 2020. The selloff comes in response to comments and announcements from AI startup Anthropic, which recently promoted its new Claude Code tool designed to modernize COBOL applications.
The sudden market reaction highlights growing investor apprehension about the impact of artificial intelligence on traditional technology companies, particularly those relying on legacy systems. February’s declines have now pushed IBM’s monthly stock performance down 26%, the steepest single-month drop for the company since at least 1968.
Claude Code Targets Legacy COBOL Systems
Claude Code is an AI-driven tool aimed at assisting in the modernization of COBOL, a programming language that has powered IBM mainframes for decades. COBOL remains critical in industries such as banking, insurance, and government operations, where legacy systems form the backbone of daily operations.
International Business Machines Corporation, IBM
According to Anthropic, Claude Code can automate portions of COBOL modernization, reducing the manual labor historically required for such projects. While this has the potential to accelerate software updates and system improvements, investors appear concerned that widespread adoption could erode IBM’s long-standing competitive advantage in the mainframe market.
Investor Concerns Over Legacy Business Impact
Most mainframe computers running COBOL are produced by IBM, making the company a central player in this specialized market. Analysts suggest that tools like Claude Code could threaten IBM’s revenue streams by enabling clients to modernize without relying as heavily on IBM’s mainframe services.
IBM shares plummeted 13% yesterday after Anthropic posted a blog explaining “How AI helps break the cost barrier to COBOL modernization.”
This is IBM’s steepest one-day drop in the last 25 years! pic.twitter.com/7ugKt2Msi0
— BeInCrypto (@beincrypto) February 24, 2026
This concern has prompted a rapid reassessment of IBM’s growth prospects. Investors are increasingly weighing the balance between IBM’s ongoing enterprise contracts and the potential disruption posed by emerging AI solutions that could make certain legacy services less indispensable.
Mainframe Business Still Holds Strategic Value
Despite the selloff, IBM’s mainframe business continues to be a key pillar of its operations. Financial institutions, insurance companies, and government agencies still depend heavily on COBOL-based systems for core processes such as transaction processing, record-keeping, and regulatory compliance.
Industry experts note that even with AI-assisted modernization, transitioning away from legacy systems is complex and may not happen rapidly. IBM still holds a significant advantage in mainframe expertise, infrastructure, and support networks, providing a buffer against short-term market volatility.
Looking Ahead: AI and Legacy Tech
The decline in IBM’s stock reflects a broader theme in technology investing: how AI innovations intersect with established industries. While AI presents opportunities for efficiency and modernization, it also introduces uncertainty for companies historically dependent on specialized, slower-evolving technologies.
As AI tools like Claude Code gain traction, IBM will need to demonstrate how it can leverage these technological shifts to enhance, rather than undermine, its core offerings. The company’s ability to innovate while maintaining strong client relationships in critical sectors will be closely watched by investors and analysts in the coming months.
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