When your biggest investor is also your biggest supplier and one of your largest customers, the accounting gets interesting. OpenAI’s confidential S-1 filing, submitted to the SEC on June 8, reveals just how tangled those relationships have become.

In the first quarter of 2026, approximately 45% of OpenAI’s total expenses were attributed to related parties. A full 72% of OpenAI’s cost of revenue in Q1 went to Microsoft and other hyperscalers.

Microsoft owns approximately 27% of OpenAI, a stake valued at around $135B after the company’s recapitalization. Microsoft has invested a total of $13B into OpenAI, with $11.6B already deployed by late 2025. It’s also the primary provider of Azure cloud infrastructure that OpenAI runs on, and revenue-sharing agreements have historically funneled a portion of OpenAI’s earnings back to Redmond.

The related-party revenue side of the equation is growing even faster. OpenAI pulled in $758M in related-party revenue during Q1, a twelve-fold increase year-over-year.

OpenAI also made $488M in non-cash equity payments for compute services during the quarter.

The infrastructure bet

The filing also disclosed $665B in commitments for future chips and data centers. OpenAI has been collaborating with Oracle and SoftBank on ventures like the Stargate project. OpenAI’s losses in the quarter came in at nearly $5B, with some of those losses attributed to outside partners.

What this means for investors

The S-1 filing is confidential for now, which means the full picture hasn’t reached public investors yet. When 72% of your cost of revenue goes to your investors, the independence of your financial results becomes a legitimate question. The SEC has historically scrutinized IPO candidates where revenue and expenses are heavily concentrated among entities with overlapping interests.