It's been a big help to the consumer—but maybe it should be a big worry to stock investors. That would be falling gas prices.
Over the past two months, unleaded gasoline prices have dropped by 18 percent, while the S&P 500 has risen nearly 4 percent. And here's why that could be trouble: Carter Worth, chief market technician at Oppenheimer, points out that every time the S&P has corrected by 5 percent or more since the market's March 2009 low, gasoline has either led that drop, or fallen with the market.
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Right now, the chart of the S&P 500 vs. unleaded gasoline shows a clear divergence:
So how will that divergence resolve itself?
"It is Oppenheimer's judgment that a garden-variety sell-off of six to nine percent in the S&P 500 is overdue and imminent," Worth wrote to CNBC.com. "And the sell-off we've seen in gasoline over the past eight weeks is a harbinger of things to come for the S&P."
Anthony Grisanti of GRZ Energy notes that the problem is clear. "Something is going to give one way or another," Grisanti said. "Either equities will break lower, or gasoline will go higher."
Still, he's less concerned about what it could mean for the market, because he believes that both gasoline and the market are pretty much where they should be. "Gasoline is trading on fundamentals," Grisanti said, "and so are stocks."
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Others say that in this environment, falling gas prices are actually a good thing. That's because they keep inflation at bay, and thus allow the Fed to continue easing without creating inflation for consumers. In fact, the Consumer Price Index reading for March actually dropped due to falling gas prices.
That's why, in the view of KKM Financial CEO Jeff Kilburg, "Cheaper gas should fuel Bernanke's QE assault vehicle to stay on the road longer and go much further than originally thought."
Michael Block, chief equity strategist at the Phoenix Partners Group, also believes that falling gas prices are a good sign. "It's good news for the U.S. consumer and for the inflation story," Block said. "I am not convinced at all that it's a sign of something bad for the consumer. What I do know is that it is making the consumers' wallets fatter."
— By CNBC's Alex Rosenberg
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