“…(Boquist et al, 1975), where g is the annual growth rate of the firm's cash flows and r is the interest rate discounting future cash flows, neglecting the possibility that the firm may ever fail. 2 Though conceptually elegant and conveniently simple, this expression predicts unrealistically long durations when compared against historical data (Leibowitz et al, 1989;Hamelink et al, 2002). For example, if a firm's cash flows grow at an annual rate 2 percentage points less than the discount rate, the equity's duration would be calculated at roughly 50 years; empirical studies, by contrast, have often found equity durations less than 10 years (Leibowitz et al, 1989;Cornell, 2000;Hamelink et al, 2002).…”