2. Our data source is the Fixed Income Securities Database jointly published by LJS Global Information Services and Arthur Warga at the University of Houston.

3. These characteristics include such things as the offering amount had to be at least $25 million and excluded medium-term notes and bonds with other embedded options (e.g., bonds that were putable or convertible). See Scott Brown and Eric Powers, “The Life Cycle of Make-Whole Call Provisions,” Working Paper, March 2011.