The U.S. and European markets are rebounding and showing much stability compared to Monday’s roller coaster. And that falls in line with the general advice: Don’t panic. But the NYT’s David Leonhardt points out a reason to maintain some level of concern: “Stocks are more highly valued than at any point from the 1940s through the mid-1990s, relative to long-term corporate earnings.” Killjoy. I still say the key to surviving a down market is to hold your position and avoid panic. That’s why I’m not selling a single share of Webvan.