Whether massive robo-signing occurred is no longer in issue. The question that needs to be investigated is why it was being done. The alleged justification—that the bankers were so busy that they cut corners—hardly seems credible given the extent of the practice.

The robo-signing largely involved assignments of mortgage notes to mortgage servicers or trusts representing the investors who put up the loan money. Assignment was necessary to give the trusts legal title to the loans. But assignment was delayed until it was necessary to foreclose on the homes, when it had to be done through the forgery and fraud of robo-signing. Why had it been delayed? Why did the banks not assign the mortgages to the trusts when and as required by law?

Here is a working hypothesis, suggested by Martin Andelman: securitized mortgages are the “pawns” used in the pawn shop known as the “repo market.” “Repos” are overnight sales and repurchases of collateral. Yale economist Gary Gorton explains that repos are the “deposit insurance” for the shadow banking system, which is now larger than the conventional banking system and is necessary for the conventional system to operate. The problem is that repos require “sales,” which means the mortgage notes have to remain free to be bought and sold. The mortgages are left unendorsed so they can be used in this repo market.