The most popular activity this time of year, besides making ill-fated resolutions and watching meaningless bowl games, is throwing out forecasts for what the coming year will bring.

Some use political shifts, some use fundamental assumptions and some use seasonal cycles.  No matter what, they're still just guesses based on historical behavior patterns.

There are many market cycles that adherents swear by - the "four year" cycle, the "new moon" cycle, the "midterm Presidential" cycle, and on and on.

I'm sure we'll touch on a few of those as the year progresses, just to sate our curiosity more than anything, so today let's discuss the "Year 0" pattern - how the stock market has performed in years ending with a zero.

For simplicity, let's just count any year ending in "0" as the first year of a new decade.  In that case, the stock market really has struggled in these years, suffering its worst losses of any other year, and one of the poorest reward/risk ratios.

Using monthly closes in the S&P 500 since 1928, less than half of years ending in "0" have closed in positive territory.  The average maximum loss during the year was -14.3%, nearly double the average maximum gain of +8.7%.  Only years ending in "2" have fared worse (just barely).

The tables below break down the years by quarter, so we can see how each of the years have performed, as well as if there are any consistent intra-year patterns.

The worst offenders:

* The 1st quarter of years ending in "2" (with a 0.2 reward/risk ratio)

* The 2nd quarter of years ending in "2" (with a -9.8% average return)

* The 4th quarter of years ending in "7" (just plain bad all around)

The best bets:

* Any year ending in "5" (with a hugely positive reward/risk)

* The 2nd quarter of years ending in "8" (rarely has gone wrong)

* The 4th quarter of years ending in "2", "4", "5" and "6" (almost always positive)

So what about 2010?

Well, overall the year has the poorest average return and % positive of any year.  Most of the weakness has been concentrated in the first two quarters; the 1st and 2nd quarters have both seen risk more than double the reward.  The 3rd and 4th quarters have been better - not gangbusters compared to some other years, but at least a positive reward/risk ratio.

Given some of the sentiment readings we're seeing now, that cycle of weakness to begin a new decade looks even more likely than usual.