In any event, another estimate of the cost of equity for SDI would be the company’s cost of long-term debt plus either a premium in the 2 to 6 percent range or plus the 6.4 percent Ibbotson premium. Ibbotson Associates also publishes the historical risk premium on common stocks over long-term government bonds (T-bonds). A recent report indicates that this risk premium is 7.5 percent.