Investors: Hold steady. Tuesday's terrorists attacks have left many frightened investors wondering whether they should dump stocks this coming Monday when the markets are tentatively set to open -- or, at the very least, rotate their holdings into companies or sectors that stand to gain from the tragedy. But the best strategy, substantiated by history, is not to do much, financial advisers counsel. "We're not having anybody do anything different" because the diversified portfolios of our clients should help protect them from volatility, says Scott Leonard, president of L.A.-based Leonard Wealth Management. Though the attack likely will slow the productivity and decrease the profits of many businesses, especially in the insurance, airline and financial industries, "it's not cataclysmic" for the economy, says Philip Cook, a certified financial planner in Torrance, Calif. "When the markets do open again, I expect to see more selling than normal. The market will drop some, but not more than somewhere between 5% and 10%." Indeed, such a plunge could even produce bargains, some planners suggest. "A lot of smart money would see a 10% downturn as a time to put money in," Leonard says. And if history repeats itself, stocks predicted to decrease in the next few days eventually will go back up. While there's no precedent for Tuesday's events, the market has recovered dramatically in the wake of other American catastrophes. According to Ned Davis Research, the Dow Jones Industrial Average lost 4.3% in the three weeks before America waged war against Iraq. Only two months later, the index rebounded by 19.8%. In another example, the day following President John F. Kennedy's assassination, the Dow lost 2.9%. Two months later, the index was up 12.4%. During the eight days of the Cuban missile crisis, the market actually gained 1.1%, then went on to gain 17.1% two months later. Of course, the biggest X factor in the current crisis is: What happens next? Another terrorist attack on U.S. soil or a substantial retaliatory attack by the U.S. would certainly fuel more panic in the markets. Given these uncertainties, holding steady remains the most reasoned approach for the individual investor.