IMO its larger than $2.7B since Fannie and Freddie back 90% of the loans in the US. Most loans are sold shortly after closing. The problem they are having is in the transfer of the loan from the originator to the investment company. They transferred ownership electronically and not the actual paper. From what I've read and seen I'd wager a significant portion of those loans are legally un-collectable.
For 12 years or so the “assignments” (transfers of ownership) were nothing more than a name change on one line of a spreadsheet,,, NEVER LEGALLY SIGNED, NOTARIZED or RECORDED AT YOUR COUNTY COURTHOUSE ... This is where the foreclosures fail ,, the lawyers are forging proper assignments (years after they should have actually occurred) and offering them as “evidence” of ownership...
The homeowners owe “somebody” , the discovery of who that “somebody” is and what they owe is being blocked... and false lenders are substituting themselves as the “party in interest” ... It’s a KLUGE.