Zero Coupon Bond Model

The zero coupon bond model is a pricing model for a Principal Token quoted in underlying. It assumes that the price of the PT is a unit of underlying discounted by an implied rate that stays constant during the term. More specifically, is assumes

$$P(t,T) =\alpha(t)\exp(-(T-t)r)$$

where $\alpha(t)$ is the PT rate, represented in the contracts as ptRate , $T$ is the maturity timestamp and $t$ is the current timestamp.