The "Championship Belt" concept comes from boxing/wresting and is the idea that every season, the previous years champion (here the Super Bowl) starts with the belt, and each time they lose they pass the belt to the winning team who becomes the new sole owner. 

https://grantland.com/the-triangle/introducing-the-nba-regular-season-championship-belt/

finished the season with the 2024 championship belt by defeating the Rams in Week 18.

Week 16: Rams successfully defend the belt against the Jets

Week 17: Rams successfully defend the belt against the Cardinals

This market closes at the conclusion of the regular season, resolving simply with the team who holds the belt after Week 18. I'll update each week with the current owner of the belt. As a fun edge case, a tie would resolve in a division into two different belts (and could resolve for multiple teams).