OpenAI has completed a massive new funding round, bringing in $40 billion and pushing its valuation to $300 billion, according to Reuters. The deal was led by Microsoft, which is also increasing its stake in the artificial intelligence company.

The financing underscores how aggressively investors continue to back leading AI developers despite growing questions about costs, competition, and the long-term path to profitability. OpenAI remains one of the most closely watched firms in the technology sector, with its products widely used by businesses and consumers.

Microsoft’s expanded commitment further tightens the relationship between the two companies, which have already been closely linked through cloud infrastructure and AI integration. The latest round is among the largest private financing deals ever reported in the sector.

The company has not publicly detailed all terms of the transaction, but the scale of the raise highlights both the intensity of investor demand and the enormous capital requirements of advanced AI development.