Actually no, we agree to provide it under two licenses, one of which is CC-BY-SA. We don't give them ownership, we give them irrevocable usage rights.

> You agree that any and all content, including without limitation any and all text, graphics, logos, tools, photographs, images, illustrations, software or source code, audio and video, animations, and product feedback (collectively, “Content”) that you provide to the public Network (collectively, “Subscriber Content”), is perpetually and irrevocably licensed to Stack Overflow on a worldwide, royalty-free, non-exclusive basis pursuant to Creative Commons licensing terms (CC BY-SA 4.0), and you grant Stack Overflow the perpetual and irrevocable right and license to access, use, process, copy, distribute, export, display and to commercially exploit such Subscriber Content, even if such Subscriber Content has been contributed and subsequently removed by you as reasonably necessary to, for example (without limitation):

They don't own the content according to the TOS, they get a license to use it (the Creative Commons Attribution-ShareAlike 4.0 license). They could still use it for AI training, but the model would have to be CC BY-SA 4.0 (not that AI companies care).

This definitely forbids the "I will not transfer it to others without permission from Stack Overflow" checkbox, as the CC BY-SA 4.0 license says "You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits."

The Stack Exchange TOS ( https://stackoverflow.com/legal/terms-of-service/public ) doesn't assign ownership - posters retain copyright, SO gets a non-exclusive license to it, and everybody else gets it under various CC wiki terms.