(U.S. Edition) It was a rough day for markets yesterday, with major stock indexes like the Dow closing down almost 2 percent. We'll look at why the market is so vulnerable right now. Afterwards, we'll discuss the New York Fed's decision to publish a new interest rate to replace the LIBOR, the London Interbank Offered Rate, the world's most widely used benchmark for short-term interest rates. Plus: A conversation with author Alisa Roth, Marketplace's former New York Bureau Chief, about her new book, "Insane: America's Criminal Treatment of Mental Illness."