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Discount Factor (DF)

The present value of $1 receivable at a future time T, derived from the zero curve: DF = e^(−rT).

Discount factors are fundamental building blocks of derivative pricing. Under continuous compounding: DF(T) = e^(−r(T)×T) where r(T) is the zero rate at maturity T. Alternatively, DF(T) = 1/(1+r)^T under annual compounding. The full SOFR zero curve generates a set of discount factors used to price all fixed-income derivatives. Σ(DF_i×δ_i) is called the 'annuity factor' or 'PV01' — it represents the PV of $1 received each period.

Formula
DF(T)=er(T)TDF(T) = e^{-r(T) \cdot T}