"Are Stock Returns and Output Growth Higher Under Democrats?" September 2025.

Paper: pdf file Abstract
Recent literature suggests that both stock returns and economic growth are significantly higher under Democratic presidential administrations. This is a puzzle in that persistent differences in stock returns seem unlikely in efficient markets, and it is not obvious why Democrats should do better. Often these kinds of results go away with more data, and this is true here. In this paper the sample is extended to 28 administrations, from Wilson-1 through Biden. While the mean stock return and the mean growth rate are higher under the Democrats, neither of the differences in means is significant at conventional significance levels.