"For so many people not going to the office as much as they have before has had a really 2seismic 3impact on 4commercial real estate."

And a 5potential problem for America's banks.

"There's no question that there is some risk in the system associated with these changes simply because so much has changed."

Across the US, offices sit 6vacant or 7underused. Average 8occupancy is less than half of where it was in March of 2020 according to data from security provider Kastle. And that is 9dragging down the value of these properties.

"The real question is for the owners of these properties, whether they are experiencing 10financial distress or will in the future."

The problem: banks lend significant money to this sector. Goldman Sachs 11estimates that 55 percent of US office loans 12sit on 13banks' balance sheets. The decrease in values puts more 14strain on already 15stressed-out banks.

"We're well aware of, of the 16concentrations people have in commercial real estate."

Federal Reserve Chair Jerome Powell remained 17confident when asked about the danger posed by commercial real estate last month.

"The banking system is, is strong, it is 18sound, it is, it is 19resilient, it's 20well capitalized."