NEW YORK (CNN/Money) - If some extremist group commits an act of terrorism on U.S. soil, what would happen to the stock market?

-- Name withheld, Long Beach, Calif.

Unfortunate as it may be, the possibility of a terrorist attack is never too far from our minds these days. That fact was reinforced just last week when another audio tape purportedly recorded by Osama bin Laden turned up on Arabic Web sites, although in this case, aside from asking for "God's blessings" for those who attacked the U.S. consulate in Jeddah, Saudi Arabia earlier this month, the thrust of the message seemed to be advocating the overthrow of the Saudi government. (For more on the tape, click here.)

Clearly, our first concern in the wake of any attack would be the health and well-being of those immediately affected. That said, however, it's only natural for investors to wonder how terrorist activity might affect the financial markets, and particularly the stock market.

No one can predict precisely how stock investors would react to an attack on U.S. soil. It would depend on a number of factors, including the severity of the attack, to what extent it truly affected the ability of the economy to function now or in the future and whether it was seen as a one-off affair or as the first in a series of attacks.

But, given how the U.S. stock market has reacted to other major disruptions in the past, I'd be surprised if an attack had lasting repercussions.

As my MONEY Magazine colleague Jason Zweig pointed out in a story he wrote in the wake of the 9/11 attacks, the stock market has absorbed some major blows in the past -- Pearl Harbor, the Cuban missile crisis, the assassination of president Kennedy, the first Gulf war, to name a few -- and, after suffering an initial setback, typically bounced back within a relatively short period of time and went on to more gains.

The reason for such resilience is that the stock market's performance is based more on what's likely to happen in the future than what's going on the present or happened in the past.

So although investors may sell at first because of the uncertainty and fear that people naturally feel in the wake of a terrorist incident, eventually logic and ration overrule anxiety and fear. And when that happens, investors once again begin to focus on what matters most to the stock market: what is the long-term economic outlook for the country and what are the long-term earnings prospects for companies whose stock is publicly traded.

Yes, the possibility of future terrorism is part of the equation. Basically, it adds to the uncertainty of profits, especially in industries like oil that may be a direct target of terrorist attacks, as well as the likelihood that we'll have to devote more resources as a nation to our security.

But unless investors are convinced that future terrorist activity will be so huge and so pervasive that it fundamentally undermines the economy and lowers the trajectory of corporate earnings, the long-term effect on returns is likely to be minor.

I don't in any way mean to suggest that we shouldn't take terrorist activity seriously. The loss of life, the fear and the feeling of anxiety terrorism causes are reasons enough for us to do our utmost to prevent such attacks. But I don't think it rates the same sort of attention or concern from a purely investing point of view, at least not if you're in the stock market for the long haul.

Walter Updegrave is a senior editor at MONEY Magazine and is the author of "We're Not in Kansas Anymore: Strategies for Retiring Rich in a Totally Changed World."