Microsoft and OpenAI finalize restructuring deal giving Microsoft 27% ownership stake

Under the newly signed agreement, Microsoft will acquire approximately 27 % of the restructured OpenAI Group PBC, valuing the AI-research firm at roughly US $500 billion, and giving Microsoft a stake worth about US $135 billion. The deal removes previous limitations on OpenAI’s fundraising path, permits broader capital access, and assigns an independent panel to verify AGI claims. Microsoft’s prior right of first refusal on computing services is removed, but its commercial ties to OpenAI continue through to 2032. Wall Street responded positively, lifting Microsoft’s market valuation above US $4 trillion.