This message has been kicking around in the media for the past few days. As for seasonality, I have some belief, but most of all I believe this year would have been a great one to sell in May and go away...
I think there is some significance to it, but like anything it's not 100%. Think more in terms of seasonality for specific stocks. For example, check out MWV, OMX, ODP, and SPLS over the years in the July-September timeframe.
Seasonality is definitely a very valuable input, but should not be relied on exclusively. Note in July Nattie Gas bottomed out precisely:
Frikkin' awesome!!! What an eye opener... I like the comment about the dip in the S&P 500 starting mid-March to pay taxes! Too bad they don't have it for specific stocks. Cash
Some other seasonal charts: *Note the gold chart - looks like SEP 1 could be a good long entry point. http://www.page88.co.za/cr/seasonal/seasonal-patterns.shtml
Since 1998? That's called "small sample bias". September and October have generally been the worst months for the market based on long-term data. The biggest and best meltdowns have occurred during those months. The "Sell in May and go away" adage is being replaced with "Sell in May, stay sober until October, so you can buy bargains that you can sell in May at a profit". You heard it here! Stay sober just a little longer.