Anthropic said Claude Code could speed up parts of COBOL modernization; IBM shares fell sharply on February 23, 2026, as news reports connected the claim to investor concerns. Neither the reported share move nor Anthropic’s description proves that AI can modernize a production mainframe quickly. The key distinction is between using AI to analyze and change code and modernizing the larger system that code depends on.
What Anthropic said Claude Code could do
Anthropic’s February 23, 2026 announcement, as described by CIO, ITPro and Investing.com reporting attributed to Reuters, presented Claude Code as an assistant for work around COBOL modernization. The tasks included mapping dependencies, documenting workflows, identifying risks, analyzing code and assisting with implementation.
Anthropic framed those tasks as a way to reduce work that can make modernization costly and slow. In a statement reproduced by CIO, the company said: “AI excels at streamlining the tasks that once made COBOL modernization cost-prohibitive. With it, your team can focus on strategy, risk assessment, and business logic while AI automates the code analysis and implementation.” This is Anthropic’s claim, not an independently validated result: the cited reports do not provide a controlled performance comparison or evidence of production outcomes.
Why IBM shares fell—and what the reports measured
News coverage reported a steep IBM share decline on Monday, February 23, 2026, in the wake of Anthropic’s announcement. CIO reported a 13% one-day drop and described it as IBM’s largest since October 2000. Investing.com, carrying Reuters attribution, reported an intraday low 10% below the prior level. Those figures refer to different reported measurements; they should not be treated as interchangeable. They are publication-reported figures, not an independently checked exchange-feed record.
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The reports associated the move with investor concern about AI’s potential effect on work tied to legacy systems, but they do not establish that Anthropic’s announcement alone caused it. Reuters’ report also said Accenture and Cognizant declined, while noting that those consulting firms were already trading lower amid broader technology-sector weakness. A single day’s share-price move records market trading, not proof that a tool works—or that IBM’s business has permanently changed.
Why IBM says code translation is not full modernization
IBM’s response focused on the gap between changing source code and changing the system around it. Rob Thomas, IBM’s Senior Vice President of Software and Chief Commercial Officer, told CIO: “Translation captures almost none of the actual complexity. The modernization challenge is not a COBOL language problem. It is everything the application runs on and integrates with.” ITPro also quoted Thomas saying, “Decades of hardware-software integration cannot be replicated by moving code.” These are IBM’s arguments, not independent findings about Claude Code.
In practical terms, rewriting or refactoring COBOL is only one possible part of a larger effort. A modernization project may also need to account for interfaces, data flows, runtime behavior, connected workloads, hardware dependencies and operational controls. Whether a particular AI-assisted approach handles those requirements depends on the work actually performed and how its results are tested and deployed.
What IBM and Anthropic’s partnership does—and does not—show
IBM and Anthropic announced a strategic enterprise-software partnership on October 7, 2025. IBM said Claude would be integrated into select products, starting with an AI-first IDE for enterprise software development, with use cases including application modernization, code generation and review, orchestration and security-oriented development. The partnership provides business context for the February announcement, but it does not show that Anthropic’s COBOL claims were independently tested or adopted through the partnership.
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IBM also said that more than 6,000 internal early adopters were using the IDE and reporting average productivity gains of 45 percent. That is IBM’s 2025 report about early testing, not a COBOL-specific or independently audited benchmark. IBM’s partnership announcement is available at IBM’s announcement.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to assess claims that AI can modernize COBOL
For an organization evaluating such a claim, the useful question is not simply whether AI can generate or change COBOL. Compare the proposed work and evidence across four dimensions:
- Task scope: Does the tool help with discovery and analysis, translate code, refactor it, support testing, or address platform migration? These are distinct tasks.
- Validation: Are changes checked through regression tests, human review and evidence from production outcomes? A code-generation demonstration alone does not answer this.
- Integration: Does the approach account for data flows, interfaces, runtime behavior and hardware dependencies, as well as source code?
- Controls: What security and governance safeguards apply, and how are deployment risk and rollback handled?
The cited coverage offers no head-to-head Anthropic-versus-IBM benchmark. Until comparative evidence is available, the claims should be judged by task, validation and system scope—not by a vendor’s description or the market reaction to it.
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