OpenAI’s new chief revenue officer, Denise Dresser, told employees that the company’s alliance with Amazon is driving enterprise growth, while its long-standing tie to Microsoft has started to limit customer reach. Since announcing Amazon’s up-to-$50 billion investment in February, inbound demand for OpenAI models on Amazon Bedrock has surged. Microsoft, which has pumped more than $13 billion into OpenAI since 2019, declined to comment on the memo. Dresser stressed that enterprises want flexibility—many already run workloads on AWS—and OpenAI needs to meet them where they are. Both OpenAI and rival Anthropic are racing to dominate the enterprise AI market ahead of possible IPOs. Anthropic’s Claude has grabbed headlines for its rapid adoption—CEO Arvind Jain at HumanX in San Francisco even called it “Claude mania.” Anthropic claims a $30 billion run rate revenue but Dresser alleges it’s inflated by roughly $8 billion due to gross accounting of partner sales. OpenAI, by contrast, reports Microsoft revenue net, aligning with public-company standards. Anthropic defends its GAAP-consistent approach, saying it’s principal on partner sales and recognizes gross revenue accordingly. Dresser also took aim at Anthropic’s compute strategy, saying it hasn’t secured enough capacity and is running on a smaller growth curve. Anthropic counters that its multi-gigawatt deal with Google and Broadcom proves otherwise. Meanwhile, OpenAI is diversifying cloud providers beyond Microsoft—adding CoreWeave, Google and Oracle—to ensure ample capacity for training and inference. Inside OpenAI, Dresser has absorbed commercial duties from Brad Lightcap and is pushing teams to focus on customers and execute as one unit. She reminded staff that while the Microsoft partnership laid the foundation, this next phase with Amazon is theirs to win.