Overview

I'll resolve this market sometime in June in the event a breach is announced later but occurred before EOM May 2026. I'll use the articles' datetime vs UTC.

Breach will be broadly defined by me. I won't bet in this market to maintain neutrality.

Context

“We’re investigating a report claiming unauthorized access to Claude Mythos Preview through one of our third-party vendor environments,” an Anthropic spokesperson told TechCrunch. The company said that, so far, it has found no evidence that the supposedly unauthorized activity has impacted Anthropic’s systems in any way.

The group in question is “interested in playing around with new models, not wreaking havoc with them,” the source told the outlet.

Articles

https://techcrunch.com/2026/04/21/unauthorized-group-has-gained-access-to-anthropics-exclusive-cyber-tool-mythos-report-claims/

https://www.bloomberg.com/news/articles/2026-04-21/anthropic-s-mythos-model-is-being-accessed-by-unauthorized-users