Behind Today's Rally: It Wasn't Just a 'Cliff' Deal

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Not everyone thinks Wednesday's big stock rally was simply due to a "Fiscal Cliff" deal.

While most observers said Congress's last-minute agreement was the main driver behind the global rally, some pros think it had more to do with new money coming into the market and prospects for more central bank easing.

UBS's Art Cashin, for one, said the fiscal cliff resolution cleared the way for fund managers to begin their traditional stock buying at the start of the year.

"It's new money for the new year," Cashin told CNBC. "It's going on globally. It's not just a flight from safety if you look at the percentage moves, many of them are identical so to me, it's assets coming in."

Cashin said that in the session's last hour, 70 to 75 percent was to the buy side.

"That put a special bid under the market," he said. "What we benefited from today is the politicians haven't run to center stage. If they do that, things could change. This is a pretty hefty move. I would look for more consolidation tomorrow."

Billionaire investor Wilbur Ross too suggested that some of the rally may just be new money coming in.

"Remember this is the first part of January a lot of institutions have an influx of new money that has to be put to work,"he told CNBC. But he didn't completely rule out a positive impact on markets from the cliff deal. "I think there was so much anxiety built up over the cliff that almost any resolution would have brought a sigh of relief," he said.

Meanwhile, Pimco's Bill Gross told CNBC that the rally was inspired by the prospect of more central bank stimulus from Japan and the U.S.

"To suggest that's it's a fiscal cliff avoided type of rally is a misconception because basically the central banks are in the process of writing lots of checks, billions of dollars worth of checks," Gross said.

The Federal Reserve just embarked on a new round of monetary stimulus, while the election of a new prime minister in Japan has led to speculation that the Bank of Japan will soon be pressured to unleash massive bond buying.

Gross echoed other observers who say that the dramatic 11th hour accord did not fundamentally change the U.S.'s long-term budgetary outlook. (Read more: Despite Cliff Deal: 'Nothing Really Has Been Fixed' .)

"The economy is being affected negatively by this package," the fund manager said, adding that the resulting "fiscal drag" from higher taxes could shave about 1.5 percent from U.S. gross domestic product.

"Ultimately you come to a point really where the government in terms of the entire package hasn't addressed spending but has addressed taxation," Gross said, branding Washington as "dysfunctional." He predicted the battle would soon come to a head once negotiations over the debt ceiling begin in earnest.