The initiative, called Pacing the Frontier, includes employees from Meta Platforms, Anthropic, OpenAI and Alphabet's Google, with support from nonprofits Guidelight AI Standards and Encode AI. Signatories include Anthropic CEO Dario Amodei and several cofounders, Meta's vice president of AI research, Dawn Song and OpenAI Chief Scientist Jakub Pachocki.

More than 1,100 employees have signed the letter.

The letter zeroes in on concerns that frontier AI models may soon be able to improve themselves, which could drastically change the future of AI.