A floating rate note (FRN) that that has no redemption date (maturity date), i.e., whose principal never matures. The note only has perpetual coupon payments which reset periodically on a fixing date based on some reference rate such as 3-mont or 6-month LIBOR.

Perpetual floating rate notes are, by nature, debt instruments. However, the perpetual status brings them closer to the class of equity instruments.