Corporations did not just decide to issue mountains of debt, much of which is low rated and of poor quality, for no reason at all. They did it, in large part, as a result of the economic and market environment created by the Fed through low interest rates and quantitative easing (QE)......The Fed removed over $4 trillion of the highest quality bonds out of the domestic market. In doing so, they pushed interest rates to historic lows. The combined effect all but forced investors to seek out higher-yielding, riskier instruments. As a result, the demand was ready and more than willing to absorb the on-coming wave of corporate supply and to do so at remarkably low yields and therefore very favorable terms for the issuers.