There has been a lot of chatter about the seasonal pattern for the S&P 500 in December, and it is bullish. StockCharts users do not need to rely on the chatter because they can chart seasonal patterns using our Seasonality Tool and see for themselves. The chart below shows the seasonal tendencies for the S&P 500 over the last twenty years. The S&P 500 has closed higher 75% of the time in March and December, and the average gain for December is 1.6%. Seasonal tendencies do not always pan out, but the S&P 500 is in a clear uptrend and the bullish seasonal pattern acts as another tailwind.