By Kate Gibson

The spread of swine flu had stock analysts on Monday drawing comparisons to the 2003 outbreak of severe acute respiratory syndrome, or SARS, but they downplayed the idea of major market disruption.

"Swine flu has the potential to become a significant global market mover if it were to develop into a global pandemic. However, it is still too early for this," said Lars Christensen, chief analyst at Danske Bank.

On Wall Street, U.S. stocks vacillated as worries that swine flu would further deepen the recession offset better-than-forecast results from Humana Inc. (HUM) and General Motor Corp.'s (GM) strategy to trim $44 billion in liabilities.

The Dow Jones Industrial Average (DJI) finished at 8,025.00, down 51.29 points, or 0.6%. The S&P 500 Index (SPX) dropped 8.72 points, or 1%, to 857.51, while the Nasdaq Composite (RIXF) shed 14.88 points, or 0.9%, to stand at 1,679.41.

"When people get nervous and scared, the first thing they want to do is sell," said Andy Brooks, head of U.S. equity trading at T. Rowe Price. Listen to Brooks.

The outbreak suspected in 149 deaths in Mexico has spread to the United States, where 40 victims of the disease have been confirmed, and to Canada, where six people are infected. .

"Over the coming weeks, swine flu is likely to either fade away as a market theme or escalate into an all-consuming market driver depending on whether or not it develops into a pandemic in the U.S. and/or other industrialized countries," said Christensen, who noted significant drops among airline stocks on fears the flu might reduce international travel and trade activity.

Disrupting travel, trade and the workplace, the SARS outbreak in 2003 lasted six months and killed 775 of the 8,000 people infected in 25 countries.

It had a significant, albeit short-lived negative impact on Asian financial markets, though the global economic impact of SARS proved quite limited, the analyst noted.

"At this stage, it is near impossible to assess the global macroeconomic impact of swine flu, but our main scenario is that the impact will be relatively limited, as was the case with SARS in 2003," said Christensen.

"We are sympathetic to the idea recalling the impact of bird flu on Asian GDPs during that scare and so understand the market's temperament with the initial headlines about various cases being found in the U.S.," said David Ader, U.S. government bond strategist at the Royal Bank of Scotland.

The Asian Development Bank said SARS cost East and Southeast Asia $18 billion or 0.6% of GDP -- 2.6% for Hong Kong, and 2% for Singapore for the first part of 2003, said Ader.

"The concern is that the flu becomes a very serious and disruptive pandemic. The last major flu pandemic scare was SARS. We expect some food export restrictions until this flu attack clears," said Frederic Dickson, chief market strategist at D.A. Davidson & Co.