With interest rates at or near record lows around the world, the corporate bond market is an attractive proposition for yield-hungry investors. Increased investor demand has allowed "zombie businesses" (failing organizations propped up by cheap credit) to secure financing by issuing risky corporate bonds. If credit costs become more expensive, the concern is that these zombie businesses could fail - potentially in dramatic fashion. In this article from Barron's, they explain what all of this means for investors.