ChatGPT-maker OpenAI has filed confidentially for an initial public offering, the company announced Monday in a blog post. The filing comes a little more than a week after its main rival, Anthropic, also filed to go public, ramping up the race between the two AI firms.

OpenAI, which was last valued at $852 billion post-money, submitted a draft registration statement to the U.S. Securities and Exchange Commission for a proposed IPO. OpenAI hasn’t shared any specifics yet. However, the company said it posted the blog because it expected a leak.