A multi-currency derivative (a quanto rate exotic) that constitutes a constant maturity swap (CMS) in which the floating leg is fixed to a foreign floating index. In other words, the interest rate on one leg is reset periodically, but with reference to a foreign market swap rate (other than LIBOR).

The other leg of the swap is generally LIBOR, but may be a fixed rate or possibly any other constant maturity rate. In this sense, a quanto CMS involves both multi-currency issues and unnatural time lags for rate payments.