Gee, about 4 times that and we'll be at a trillion. In the 1929 crash, you also find attempts (some by individuals) to support the market.
It's better known as the Exchange Stabilization Fund. http://www.treasury.gov/resource-center/international/ESF/Documents/Trunc + Notes.pdf
In this particular case I highly doubt this is true. So far this only qualifies as a market correction. The markets haven't fallen enough yet for the PPT to get involved. A Greek collapse may be an event that would require them to get involved and I suspect they have the ability to assemble many banks to support whatever actions they need to take and have the ability to either hedge or exit their position w/o taking on too much exposure or risking such a loss the OP stated.
USPS has 120,000 too many employers and ahhhhhhh fuck it. You know you'll miss me when I'm gone. You'll have to find someone else to stalk, fucking dirtbag