Monthly Returns During Presidential and Congressional Election Years

Do hopes and fears of U.S. election outcomes, associated political machinations, alter the "normal" seasonal variation in monthly stock market returns? To check, we compare average returns and variabilities (standard deviations of returns) by calendar month for the S&P 500 Index during years with and without quadrennial U.S. presidential elections and biennial congressional elections. Using monthly S&P 500 Index closes over the period December 1927 through July 2020 (nearly 93 years), we find that: