For those confused by the cornucopia of assorted debt ceiling "plans" out in circulation, Citi's Amitabh Arora has released the definitive guide for what plan does what in terms of proposed deficit reduction, probability of passage of the Congress, Senate and the President, and likely outcome to the US rating. As table 1 below shows, UBS' prescient call from last Thursday that a US downgrade is inevitable, was spot on. It also explains why the entire sellside industry, and media, have been in damage control over what now appears to be an inevitable AA rating of the world's reserve currency. Alas, just like with Lehman, nobody really has any idea what will happen to capital markets once the Poor Standards or Moody's headline of a AA cut hits the tape: one thing is certain - there are trillions in US invested money market funds, structured finance debt and munis that have rating mandates and demand a super secure (AAA) threshold, and especially an A-1+ short-term rating. Should there be a massive flow out of these securities and into other asset classes, the outcome is absolutely unpredictable. More importantly, Citi touches on a topic that has not seen prominent mention anywhere else: namely the acceleration of the GSEs status from conservatorship to receivership should there be no prompt resolution on the debt ceiling. For agency paper holders this may be a topic that merits much more diligence.