While patriotically buying US equities, or Intrade contracts, is 'believed' to reflexively improve the odds of the incumbent reaching a second term, the correlation between Obama's lead over Romney and stocks is actually not that high. The most highly correlated 'vehicle' for 'impacting' the odds of an Obama victory is, according to empirical data, the CRB Index.
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(h/t @Not_Jim_Cramer)