According to CoinMeta, after Anthropic promoted its ability to transform the old COBOL system using Claude Code, the stock price of IBM tumbled by 13.2% in a single day. Eight months later, OpenAI announced that the highest success rate in the code migration tests for the GPT-6 series reached 97.9%. The COBOL language has been widely used in banking transactions, ATM, and insurance systems since the 1950s; many programs have been running for decades, and some business rules exist only within the code. OpenAI tested the ability to rewrite COBOL programs in languages such as C++, Java, Python, and Rust, requiring the new and old programs to produce identical outputs byte for byte during testing. The success rate at lower inference levels was 86.6%, compared to just 5.4% for the previous generation GPT-5.6. After increasing the inference level, the success rate further rose to 97.9%. OpenAI also open-sourced Multilangbench, and required AI to write a database engine compatible with SQLite from scratch using 20 different programming languages; the average test pass rate for GPT-6 reached 87.4%.