Function B_Yield_ISMA(Sett_d As Date, Mat_d As Date, Cpn As Double, Price As Double) As Double
' Calculates the yield of a coupon bearing bond (ISMA)
    Dim L As Double, t As Double, sz As Double, T1 As Double, T2 As Double, T3 As Double
    Dim k1 As Double, k2 As Double
    Dim n As Long
    L = Application.Days360(Sett_d, Mat_d) / 360
    n = Int(L)
    t = L - n
    sz = Cpn * (1 - t)
    T1 = Application.Rate(L, Cpn, -Price, 100)
        If IsError(T1) Then T2 = -1 Else k1 = (-Application.PV(T1, n, Cpn, 100) + Cpn) / (1 + T1) ^ t - sz
                 T2 = T1 + 0.00005
                 k2 = (-Application.PV(T2, n, Cpn, 100) + Cpn) / (1 + T2) ^ t - sz
                While Abs(k2 - Price) > 0.00005
                    T3 = T1 + (Price - k1) * (T2 - T1) / (k2 - k1)
                    T1 = T2
                    k1 = k2
                    T2 = T3
                    k2 = (-Application.PV(T2, n, Cpn, 100) + Cpn) / (1 + T2) ^ t - sz
                Wend
    B_Yield_ISMA = T2
End Function