NEW YORK (CNN/Money) - Stocks have run into a patch of trouble lately, with techs in particular getting hit hard, and Wall Street is ascribing all sorts of reasons to why this has happened.

The market has gone too far, too fast. The high price of oil and the drop in the dollar are troubling. With the economy still shedding jobs, the sustained recovery stocks are priced for is by no means assured. And so on.

But maybe what we're really seeing is a twist on the January effect.

The January effect is the tendency of stocks that have performed poorly through the year to underperform the market in December and see a pop as the new year begins. The reason? Fund managers scuttle their losing stocks for tax purposes at the end of the year, and once this artificial selling pressure is removed they can take gains. Smaller stocks, because they trade more thinly, tend to see the biggest gains, but the effect is by no means confined to them.

Okay, so it isn't even close to January right now. But there are a host of mutual funds that end their fiscal years in October now -- nearly as many as in December. So there are a host a funds that, if they're going to do any tax-loss selling, have to do it now.

Why would they be selling the stuff that's been surging? No way to get a tax loss on that stuff.

Only if they bought those shares over the past year. Look at something like Lucent -- yes, it's tripled in price since last October, but it's way below where it started out 2002 at. And don't even talk about where it was in 2000.

Add to that the matter of what you want to show investors on your books when you close out your year. It's nice to have big gains, but if you've done it on the back of volatile, speculative issues like Lucent, people might start thinking you're a cowboy. And think about putting their money with another fund.

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Makes for a sloppy market for now, but it may mean that as October wears on stocks could move higher. Particularly as the many underperforming hedge funds, which generally work on calendar years, try to catch up.