NEW YORK (CNNMoney) - The Pittsburgh Steelers' fifth Super Bowl win could also signal a positive year for stocks, if the Super Bowl stock indicator is to be believed.

The somewhat questionable market barometer suggests that a Super Bowl win by a team that played in the National Football League before it merged with the American Football League in 1970 results in a gain in the Dow during the year, while a win for an old AFL team results in a loss for the Dow. Sunday the Steelers beat the Seattle Seahawks 21-10.

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Certainly the indicator worked in each of the Steelers' four previous Super Bowl wins, as the Dow posted an average gain of just less than 15 percent in those years.

Going into trading Monday, the Dow is up 0.7 percent for the year.

Of course it's probably safer to criticize beloved Steelers running back Jerome Bettis in either Pittsburgh or his hometown of Detroit today than it is to base investment decisions on the outcome of a football game.

Some market experts say that other indicators, such as the January effect, are far more valid sign posts for how stocks will do in the year. The January effect says a gain by the Standard & Poor's 500 index in the first month of the year points to a positive year for stocks.

"I don't believe in these kinds of indicators, but I do believe in momentum," said Ned Riley, chief investment officer at Riley Asset Management. "The momentum in January was good and I do think we will have an up year, but not because of an indicator."

But even with an uneven record the last eight seasons, the Super Bowl stock indicator has an impressive track record for accurately predicting the market.

It proved correct in 2004, when the Dow finished slightly lower following the win by the old AFL New England Patriots, even as other major U.S. stock indexes posted gains.

That win gave it a success rate between 77 to 81 percent, depending on if you count the two Super Bowl wins by franchises that the NFL counts as being created after the merger.

Of course one of the other misses came in 2004, when the Patriots beat the expansion Carolina Panthers, and the Dow still posted a gain for the year.

If the presence of any post-merger franchise in the big game invalidates the indicator, then you can truly ignore the results Sunday, since the losing Seahawks were formed in 1975.

For a closer look at the stock market's January effect, click here.