A CNBC analysis of S&P 500 returns from 1980 through 2024 shows the index rose an average of 13.7% one year after midterm elections, with positive returns in 91% of cases. The S&P 500 was up after all 11 midterms from 1982 through 2022. Historically, markets prefer divided government, with the S&P 500 averaging a 15% gain one year after elections that resulted in no single party control, compared to 11.5% under single-party control. However, factors like Federal Reserve policy, corporate earnings, AI trends, geopolitics, and the bond market ultimately matter more than elections, according to Société Générale and Deutsche Bank.