The month of September is, infamously, a period of weak seasonality for the stock market. According to Dow Jones Market Data, the Dow Jones Industrial Average (DJI) finished the month higher just 41.7% of the time dating back to 1987, while the S&P 500 Index (SPX) rose only 44.3% of the time since 1928. In addition, the indexes averaged a monthly deficit of 1.1% and 1.2%, respectively. One of the most unfavorable stocks to own in September is real estate investment trust (REIT) American Tower Corp (NYSE:AMT ...