ChatGPT is owned by OpenAI, with governance overseen by the OpenAI Foundation....

https://wiki-spirit.win/index.php/What_Are_the_Four_Dimensions_of_ChatGPT_Ownership_in_Plain_English

ChatGPT is owned by OpenAI, with governance overseen by the OpenAI Foundation. While Microsoft is a major investor and partner, it is not the parent company