Birinyi, an equity trader at Salomon Brothers Inc. in the 1980s, was one of the first investors to recommend buying when stocks bottomed in 2009. He stayed bullish through the S&P 500's decline of 16 percent in 2010 and last year's tumble to 1,099.23 on Oct. 3 from 1,363.61 on April 29.

'We Were Uncomfortable'

"Quite frankly, when the market got down 19 percent, we were uncomfortable," he said in a Jan. 4 phone interview. "But we were uncomfortable in 2010 when the market went down 15 percent, and it ended up recovering."

U.S. equities are in the third of four bull market stages, in which investors accept the rally that gathered momentum in the first two, according to Birinyi's analysis. He said this phase, which started around July, should end in 2012 with a gain of at least 8 percent. The bull market's final phase of "exuberance" has lifted the S&P 500 an average of 39 percent in the five advances since 1962, he said.

S&P 500 earnings have beaten estimates for the past 11 quarters and are forecast to climb above $100 a share in 2012, according to analyst projections compiled by Bloomberg. A ratio of debt to assets for S&P 500 companies reached its lowest point since at least 2002 in the third quarter, Bloomberg data show.

Bulls Under Pressure

Bulls such as Birinyi came under pressure in the second half of 2011 as the S&P 500 tumbled 5.7 percent in August and 7.2 percent in September. It lost 4.5 percent on Aug. 18 when the Federal Reserve said factory production in the Philadelphia region reached a 29-month low. The index lost more than 5 percent over two days twice before bottoming on Oct. 3, the first time after the Fed cited risks to the economy on Sept. 21, the second after consumer spending slowed on Sept. 30.

Stock swings increased as economists cut their forecast for 2012 GDP growth from 3.3 percent in February to 2 percent in October. Roubini, the co-founder and chairman of Roubini Global Economics LLC in New York, put chances of a contraction in developed economies at 60 percent and said investment gains would prove temporary. The S&P 500 is up 4.5 percent since he spoke Oct. 18 at an Asset Allocation Summit in London. Roubini declined to comment on his outlook.

Shilling said in September that equities were likely to drop and that earnings would fall short of estimates. He predicted in August that the U.S. would enter a recession this year. While he missed the 17 percent rally that began Oct. 3, he's betting on a retreat as consumers save, the economy shrinks and profits fall.

'Tough-Going'

"It's probably tough-going for the equity markets this year because the expectations are that economy is going to be strong and corporate profits are going up," Shilling, who contributes to Bloomberg View, said in a Jan. 4 phone interview. "I don't think that's realistic. I think we'll probably have a decline in earnings, which feeds off the forecast of a moderate recession."

Michael Shaoul told clients of Marketfield Asset Management on Sept. 14 and Sept. 23 to hold stocks because the decline wouldn't last. While investors were right to be wary of Europe's debt crisis, calls for a U.S. recession were unwarranted, according to Shaoul, who helps oversee $1 billion in New York.

'Violent Market'

"This was a particularly violent market," Shaoul said in a Jan. 5 phone interview. "At some point in time those negative things are going to matter a great deal, but not at this point in the cycle. It still looks to me that the U.S. equity market should be able to surpass that 2011 high."