IBM stock price drops 13% after Anthropic presents 'Automating Legacy System Modernization with COBOL' on Claude Code

On February 23, 2026, Anthropic published a blog explaining 'How to Modernize Legacy Systems Using COBOL with Claude Code.' After this blog was published, IBM's stock price plummeted by more than 13%.

IBM is the latest AI casualty. Shares tank 13% on Anthropic programming language threat
https://www.cnbc.com/2026/02/23/ibm-is-the-latest-ai-casualty-shares-are-tanking-on-anthropic-cobol-threat.html

Anthropic touts AI for COBOL, IBM stock takes a hit • The Register
https://www.theregister.com/2026/02/23/ibm_share_dive_anthropic_cobol/

IBM Shares Crater 13% After Anthropic Says Claude Code Can Tackle COBOL Modernization - Slashdot
https://slashdot.org/story/26/02/23/2110221/ibm-shares-crater-13-after-anthropic-says-claude-code-can-tackle-cobol-modernization

One of IBM's main businesses is 'modernization,' which involves updating legacy systems written in COBOL with the latest technology. IBM also sells mainframes optimized for large-scale transaction processing, and COBOL is often used in these as well. In fact, COBOL is used in many of the core systems of financial institutions and government agencies, and in the United States, approximately 95% of ATM transactions are related to legacy systems written in COBOL.

However, the number of engineers familiar with COBOL is decreasing year by year, and COBOL modernization work is often extremely difficult due to inadequate documentation and difficulty in understanding implicit business rules.

However, Anthropic reported in a blog post that Claude Code can automate the 'investigative and analytical work' that accounts for most of the complexity in this modernization. According to Anthropic, 'investigative and analytical work' that would take a human analyst several months can be completed in a short period of time with Claude Code.

How AI helps break the cost barrier to COBOL modernization | Claude
https://claude.com/blog/how-ai-helps-break-cost-barrier-cobol-modernization

After Anthropic reported on the usefulness of Claude Code for COBOL modernization, IBM's stock price fell 13%, meaning that IBM's stock price has fallen by more than 24% since the start of 2026.

On the same day, Anthropic also announced 'Claude Code Security,' a service that can scan and detect vulnerabilities in code. CNBC points out that this announcement also caused stock prices of security-related companies to fall.

'Claude Code Security' has arrived, scanning for vulnerabilities in code and suggesting fixes - GIGAZINE