Today’s Chart of the Day comes from EquityClock.com (@EquityClock). It’s a seasonality chart showing the average performance of the S&P 500 throughout the year, using 20 years of data. September has historically been the worst month for the S&P 500, with an average loss of 0.80%. Assuming we don’t get some sort of epic sell-off tomorrow, the S&P 500 will likely close higher for the seventh straight month. As we start the new month, it’s important to keep this seasonal headwind in mind. Will it be enough to end the S&P 500’s monthly winning streak? To be fair, seasonality has been a headwind since May, and it hasn’t stopped the S&P 500 from rising nearly 8%. That sort of resilience is a testament to how strong the underlying trend is at the moment. It’s also important to consider that the calendar flips bullish for about six months after September (around mid-October). So, any potential weakness in September could prove to be a buying opportunity if history is any guide.