(U.S. Edition) The Dow dropped almost 1,200 points yesterday in a record plunge. But no need to panic yet. We'll look at what may have triggered the sell-off. Afterwards, we'll talk to Marketplace economics correspondent Chris Farrell about why some people are actually relieved that the market took that huge plunge, and then we'll discuss how markets in Asia are faring, following volatility in the U.S.