Why the long ABS?

Gillian Tett comments on the large supersenior ABS holdings at Merrill and UBS in the FT backed by mortgages on properties like the fine abode above:

Most notably, as these banks have pumped out CDOs, they have been selling the other tranches of debt to outside investors – while retaining the super-senior piece on their books. Sometimes they did this simply to keep the CDO machine running

Absolutely. And also as a funding arbitrage: for a bank that funds at Libor flat and views supersenior as risk free supersenior paying Libor plus ten is a good investment. Tett continues:

[Since] super-senior debt carried the AAA tag, banks were only required to post a wafer-thin sliver of capital against these assets

Again true, but I doubt that the advantageous reg. cap. position of these assets was that important. Any low volatility bond would do in a VAR setting, or any internally highly rated one under Basel 2 in the banking book. And there are plenty of AAAs that yield more than Libor plus ten. The real issue is the risk assessment: some banks managed to persuade themselves this paper was risk free. And that brings us nicely to an article in the WSJ on how exactly the firm got to that assessment. Enjoy.