OpenAI and Anthropic Count Revenue Differently — and IPO Investors Are Paying Attention
OpenAI reports $25 billion in ARR. Anthropic reports $19 billion. On the surface that looks like a straightforward competitive gap — but a Forbes investigation finds the two numbers aren't actually comparable, because the companies apply materially different accounting treatments to revenue generated through compute-reseller partnerships. The discrepancy is significant enough that SEC reviewers are likely to require explicit accounting policy disclosures in each company's S-1 filing, and investors already modeling relative valuations may be working from fundamentally apples-to-oranges data.
Dig into the underlying metrics and the picture shifts considerably. Anthropic's ARR grew from $9 billion at the end of 2025 to $19 billion by March 2026 — a 111% increase in roughly three months. OpenAI's growth rate over the same period, while strong in absolute terms, trails that percentage trajectory. On capital efficiency, Morningstar calculates Anthropic generates $0.23 in ARR per dollar raised versus OpenAI's $0.11, a ratio that matters a great deal to institutional investors weighing how much dilution each dollar of funding is buying.
The accounting question isn't academic. As both companies prepare what could be among the largest tech IPOs in history, the SEC's standard process of scrutinizing revenue recognition policies will force a reckoning with how each company defines and counts its top line. That process could require restatements, reframe competitive narratives, and meaningfully alter the valuations investors assign before either stock begins trading.