Actuarial Notes

Convertible m-thly

Study guide: Exam FM-2

A Nominal Interest Rate is convertible m-thly (or compounded m times per year) when interest is credited m times per year at the periodic rate i^{(m)}/m. The equivalent effective annual rate is:

1 + i = \left(1 + \frac{i^{(m)}}{m}\right)^m

  • Common cases: m=2 (semi-annual), m=4 (quarterly), m=12 (monthly), m=365 (daily).
  • As m \to \infty, the nominal rate convertible m-thly approaches continuous compounding and the Force of Interest \delta = \ln(1+i).

Monthly Rate to Annual Effective Rate A savings account pays a nominal rate of 6% convertible monthly (m=12). Find the equivalent effective annual rate.

Answer 1 + i = \left(1 + \frac{0.06}{12}\right)^{12} = (1.005)^{12} = 1.06168 i = 6.168\%