What Is the Risk-Free Rate?
The risk-free rate represents what an investor can earn without taking any credit risk, making it the floor for all expected returns: nobody would accept a risky investment priced to return less than a guaranteed one. Truly riskless assets do not exist, so markets use securities backed by the full faith and credit of the US government as the closest real-world substitute.
Even Treasuries are only free of default risk, not of all risk. Their prices still fluctuate with interest rates, and inflation can erode the purchasing power of their fixed payments. The convention persists because the probability of the US government failing to pay its debt is treated as effectively zero for valuation purposes.
Which Rate to Use
The proxy should match the horizon of the cash flows being discounted. For company valuations, where cash flows stretch decades into the future, the standard choice is the yield on the ten-year US Treasury note, with some practitioners preferring the twenty-year or thirty-year bond for even longer-duration analyses. Short-dated Treasury bills, typically the three-month maturity, serve as the risk-free benchmark for money market and short-horizon calculations.
Consistency matters more than the specific tenor. The risk-free rate, the equity risk premium, and the cash flows must all be expressed in the same currency and inflation basis: a US dollar nominal DCF pairs a nominal Treasury yield with a US ERP, while a valuation in another currency requires that government's local-currency yield or an adjusted rate.
Why It Matters
The risk-free rate is the first term in CAPM, Cost of Equity = Risk-Free Rate + Beta x Equity Risk Premium, and it also underpins the cost of debt, since corporate borrowing costs are quoted as a spread over Treasuries. When the ten-year yield rises from 2% to 4%, discount rates rise across the board, present values of future cash flows fall, and valuations compress, which is a large part of why growth stocks are so sensitive to rate moves.
For students and analysts, the practical takeaways are knowing where to pull the number, quoting the current ten-year Treasury yield in interviews, and understanding its mechanical role: holding everything else constant, a higher risk-free rate means a higher WACC and a lower DCF value.
