U.S. markets closed lower on Monday as major indices fell under pressure from a late-day selloff in technology shares, with investor sentiment appearing cautious amid shifting tech sector dynamics and corporate structural changes.

The Dow Jones Industrial Average shed 98.60 points, or 0.24%, closing at 41,218.8. The NASDAQ Composite dropped 133.49 points, or 0.74%, ending at 17,844.2. The S&P 500 lost 36.29 points, or 0.64%, finishing at 5,650.38.

All three indices showed gains through the early afternoon before reversing course into the red. Relative volume metrics spiked as selling accelerated into the close, especially within tech-heavy NASDAQ components.

The tech sector was in focus not only for price action, but also because of major structural news from OpenAI. In a significant governance update, CEO Sam Altman announced the company's transition from a capped-profit LLC to a Public Benefit Corporation (PBC). OpenAI will continue to be controlled by its founding nonprofit, which will also become a significant shareholder.

“We want our nonprofit to be the largest and most effective nonprofit in history... to enable the highest-leverage outcomes for people,” Altman stated in a letter to stakeholders. He emphasized that the restructuring is not a sale, but a simplification to better align capital access with the company’s mission.

Altman reiterated that OpenAI’s founding principle remains unchanged: ensuring that artificial general intelligence (AGI) benefits all of humanity. “We believe this is the best path forward—AGI should enable all of humanity to benefit each other,” he wrote.

While the market digests OpenAI’s pivot, broader sentiment reflects a growing tension between AI’s promise and its evolving regulatory and capital frameworks. Altman noted that usage demand far exceeds capacity, with users “wanting to use it much more... for even more wonderful things.”

As AI firms continue to scale and require immense capital for model training and deployment, OpenAI’s move may set a precedent for others aiming to balance societal goals with financial sustainability.