Goldman Sachs put out a research note on Oct. 26 highlighting median S&P 500 index returns in the months following presidential elections going back to 1976. Since that time, the S&P 500 has returned approximately 10% total returns in the 12 months following a presidential election - regardless of the winner's party affiliation. Their findings also noted that Republican administrations see higher returns in the short-term, but over the entire four-year term, stocks have posted higher returns under Democrats.