NEW YORK ( TheStreet) -- If stocks continue to rally until New Year's, it probably has nothing to do with the Big Guy.

Instead, much of the year-end buying in stocks -- traditionally called the Santa Claus rally -- is the work of hedge funds cleaning up their portfolios to look good for clients.

"This Santa Claus rally is a momentum driven rally that has everything to do with liquidity and piling into yesterday's winners for managers to be able to show how smart they are and by no means an indicator of where market will be 3 months to 6 months from now," said Jeff Sica, founder, president and chief investment officer of SICA Wealth Management.

The reason hedge funds can get away with this, Sica explains, is that they often don't need to disclose WHEN they bough the stock. It's a long-held practice known on the Street as " window dressing."

The one downside is that hedge funds often unload those very same stocks after New Year's, so the market could be headed for an early sell-off in 2015.

Other pros have their own interpretation of what's causing this year-end rally.

"I would argue we probably already had quite a Santa Claus rally, but some of that was because of the pullback in October and November," said Stuart Freeman, chief equity strategist at Wells Fargo Advisors in an interview with TheStreet.

The Dow is up 11.9% since Oct. 15, when it saw an intraday drop of 460 points. 

Still, Santa Claus rallies are not unusual.

"Since 1969 the Santa Claus rally has yielded positive returns in 34 of the past 44 holiday seasons-the last five trading days of the year and the first two trading days after New Year's," said Bill Stone, chief investment strategist at PNC Asset Management Group in a note. "The average cumulative return over these days is 1.6%, and returns are positive in each of the nine days of the rally, on average."

-- Written by Scott Gamm in New York.

Follow @ScottGamm

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.

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