The stock market seems to like what it sees in September. So far…

The cruelest month of them all for equities is barely underway but, given the economic backdrop here in 2010, the odds of seeing a ‘+’ sign in front of the month-end result seems quite unlikely, though the ‘-’ sign in front of the August number might increase those chances just a bit. Mark Hulbert at MarketWatch files this report on some of the statistics behind September’s well deserved reputation for being a miserable month for stocks.

I have good news and bad news when it comes to slicing and dicing the historical data as it pertains to September.

The good news is that it is possible, by carefully reading the statistical tea leaves, to get advance insight into whether any given month is likely to do better or worse than average.

The bad news: Those tea leaves provide no such hope that this September will be able to beat its historical reputation as being awful for stocks.

Let me begin by reviewing the dreadful details of September’s record. Since 1896, when the Dow Jones Industrial Average was created, the Dow has lost an average of 1.15% in September. The average gain for all other months is 0.71%. That spread of 1.86 percentage points is statistically significant at the 95% confidence level that statisticians often use to determine if a pattern is most likely genuine.

So much for the theory that a bad August could see a bounce in September. Over more than a century of trading, the data shows that stocks lose an average of 2.7 percent in September when they declined in August and entered the new month with a year-to-date loss.