In a B.I.G. Tips report last week, we highlighted the historical performance of the Dow Jones Industrial Average (DJIA) during the month of September. In that report, we noted that September is the only month of the year where the DJIA has averaged negative returns over the last 20, 50, and 100 years. Needless to say, in its entirety, September hasn't necessarily been friendly to bulls. There is a caveat, however. While September has historically been weak for equities, performance during the month has really varied widely between the first and last half.