CITIGROUP is lucky that Muammar el-Qaddafi was killed when he was. The Libyan leader’s death diverted attention from a lethal article involving Citigroup that deserved more attention because it helps to explain why many average Americans have expressed support for the Occupy Wall Street movement. The news was that Citigroup had to pay a $285 million fine to settle a case in which, with one hand, Citibank sold a package of toxic mortgage-backed securities to unsuspecting customers — securities that it knew were likely to go bust — and, with the other hand, shorted the same securities — that is, bet millions of dollars that they would go bust.