Shares of Boeing are indicated higher after the company reached a tentative agreement with their ... [+] machinist union. (Photo by Samuel Corum/Getty Images)Getty ImagesKey Takeaways September Historically Brings Volatility, S&P 500 Drops 4.2% This Week Jobs Report And Fed Uncertainty Contribute To Major Market Declines Upcoming CPI, PPI Reports Likely To Trigger Further Market SensitivityIt was a rough first week of the month for stocks. On Friday, the S&P 500 fell 1.7%, ending the week 4.2% lower. The Na ...