Changing rules

Mutual fund investors are learning an important rule of 21st century economics. The world is changing but stock prices can still go down. You thought that was obvious, didn't you? And it is, at least in theory. But many investors may have needed to see and feel it happen, as they are doing right now, because they're not sure what rules apply any more. They hear all the time about a new economy superseding the old. They have seen with their own eyes that stocks in this economy can keep rising for years after the market was deemed overpriced by conventional measures such as price-to-book-va...