In June they just committed to deploying an additional $250 billion https://www.wsj.com/articles/fed-will-amass-corporate-bond-p...
Add this to the existing billions of debt already purchased and we could easily be at half a trillion dollars of independent fed action to buy corporate debt in a short time frame.
The CARES act also reduced corporate taxes by 210 billion. So There is at least half a trillion dollars not mentioned in articles like the one from NPR.
The CARES act separately authorized 500 billion just to the largest corporations in America. Some of the additional hundreds of billions deployed to "small" businesses is really to large companies as well.
It would be great to get a detailed breakdown of what the fed is doing, I am certainly not doing it justice in my description.