It’s the commercial mortgage backed securities market.
Remember 2008 when they bundled up all those home mortgages that were based on shitty unpayable loans and sold off securities to retirement funds etc? But then people couldn’t pay and the entire economy imploded resulting in massive bank failures?
Same deal. All those office space loans have been collateralized into securities. The 1% and the banking industry understand perfectly that if they don’t force people to return to office, the entire system will implode again. Even after Dodd Frank the regulations on over the counter derivatives are still mostly non existent.