you are getting all your concepts wrong.
the entity you speak of is not a private entity it is a government one that allows the privatization of all gains (does not profit) and socializes loss (takes on "pays" losses for private enterprise causing that long number you quoted)
They operate as a corporation. Would you like me to show you where in the US Code the "United States" is defined as a corporation?
Corporations can only operate that far in the red through bankruptcy. Please read through the US Code section 12 several times as I have. After you have done that, and maybe read Modern Money Mechanics published by the Federal Reserve, and I will be happy to discuss this further with you.