Biggest one-day drop since October 2000: $IBM got hit by an AI “squeeze”

On Monday IBM experienced its worst session in more than 25 years, with the stock falling about 13% — the market apparently reacted to reports that Anthropic, with its tool Claude Code, can significantly accelerate COBOL modernization. And COBOL is precisely one of the reasons why a large number of banks, insurers, and government bodies still rely on IBM mainframes. Investors read it simply: if the “rewriting” of old systems becomes cheaper and faster, it could, over time, weaken one of IBM’s traditional pillars.

What I find important about this is the broader context. This isn’t just a single headline about COBOL. By February IBM was already down roughly 27%, and the entire “legacy” technology spectrum takes a hit whenever someone shows a new AI tool that makes cheaper the work that historically supported consulting budgets, licenses, or long projects. The counterargument is also strong: customers have had various ways to migrate off mainframes for years, and just as often they stay, because reliability, security, and the risk of change are more costly to them than the hardware or licenses themselves.