No Permits Exchanged? A state issued marketable permits for sulfur dioxide emissions to several electricity generators. Most of the permits were given to the utilities with the oldest generating...

No Permits Exchanged? A state issued marketable permits for sulfur dioxide emissions to several electricity generators. Most of the permits were given to the utilities with the oldest generating facilities. One year later, none of the permits had been bought or sold. What could explain the absence of permit exchanges?