What is the risk-free rate and is it really risk-free?

The short answer

The risk-free rate is a foundational concept in finance: the return one can earn without bearing any default risk. In equity valuation, it is the discount rate from which all other returns are built — equity risk premium, credit spreads and term premiums all reference it. The Capital Asset Pricing Model rests on its existence.

In practice, the 3-month US Treasury bill is the global benchmark. Its yield is treated as risk-free because the US government, with monetary sovereignty over the dollar, can in principle always meet nominal obligations.

But “default-free” is not the same as “risk-free”. Holders face inflation risk (real return uncertainty), reinvestment risk (rolling at lower rates), and for non-US holders, currency risk. The label persists for analytical convenience, not because the underlying instrument is truly free of risk.

→ New to bonds? Real vs nominal returns

What the data shows

FRED data on US Treasury bill yields (1934-2024) reveals the fragility of the risk-free label:

• Real T-bill returns averaged -1.0% annually from 1940 to 1979 once inflation is netted out
• The 1970s alone saw cumulative real T-bill returns of -27% as inflation outran short rates
• The 2009-2021 zero-rate era produced 12 consecutive years of negative real T-bill returns averaging -1.5% per year
• Foreign holders saw the dollar lose 30-50% against the euro, yen and other major currencies during specific cycles, creating large FX losses on dollar T-bills

The exception worth noting: in deflationary regimes (1930s, parts of 2008-2010, 2020), nominal T-bills delivered positive real returns even at low yields, because falling prices increased their purchasing power. The “riskiness” of the risk-free rate is regime-dependent.

→ Dataset: US 3-month Treasury bill dataset

Why it happens — the macro mechanism

The risk-free rate concept holds in theory but degrades in practice through three channels.

Inflation as a hidden tax. A nominal T-bill yielding 2% with 4% inflation produces a -2% real return. The investor receives every promised dollar, but the purchasing power of those dollars erodes. This is why Robert Shiller and others advocate for inflation-protected securities as the “true” risk-free instrument when defining real returns. Inflation regimes determine the magnitude of this tax.

Reinvestment risk on rolling positions. An investor rolling 3-month T-bills cannot lock in a long-term yield. When rates fall — as they did in 2009-2021 — the rollover yield declines toward zero, eroding compound returns. The 4% rule for retirement spending was originally calibrated assuming positive real T-bill returns, an assumption that broke down post-2008. Monetary regimes set the rollover trajectory.

Sovereign credit reality. Even US Treasury credit is not absolute. The 2011 S&P downgrade from AAA to AA+ demonstrated that ratings agencies acknowledge marginal default risk. The 2023 Fitch downgrade reinforced this. Other sovereign debt (Italy, Greece) has experienced periodic default scares despite developed-market status.

Synthesis by regime: in stable low-inflation regimes the risk-free label approximates reality; in inflationary regimes it becomes a misnomer; in deflationary or crisis regimes it can outperform expectations.

The risk-free rate is the cleanest fiction in finance — necessary for theory, dangerous when taken literally.

→ Framework: Monetary regimes pillar

What it means for different economic actors

Savers using money market funds and T-bills as cash equivalents face real purchasing power erosion in inflationary regimes, even though nominal balances are preserved.

Investors use the risk-free rate as the foundation of every valuation model. When the risk-free rate is artificially suppressed (financial repression), all asset valuations are distorted upward — equity multiples expand, credit spreads compress, and risk-asset prices inflate.

Pension funds with long-dated liabilities discount future obligations using risk-free curves. Suppressed risk-free rates can mechanically inflate liability values, creating accounting funding shortfalls even when underlying solvency is unchanged.

A common error is treating the risk-free label as protection against all forms of loss. T-bills protect against default risk only; inflation, FX and reinvestment risks remain fully active.

Practical observation

Go deeper

Related questions

• Why do real yields matter more than nominal yields?
• What is the term structure of interest rates?
• What is financial repression?
• What are TIPS and how do they work?

Frequently asked questions

How is the risk-free rate selected for valuation models?

The convention varies by purpose. For short-term applications, the 3-month T-bill yield is standard. For valuing long-duration cash flows like equities, practitioners typically use the 10-year Treasury yield or even longer-dated bonds to match the horizon of the cash flows. Aswath Damodaran’s framework suggests matching the duration of the cash flows to the duration of the risk-free instrument used. The choice can change valuation outputs by 10-30% in DCF models.

Are German Bunds or Japanese JGBs also risk-free?

For investors in their home currencies, yes, in the same theoretical sense as US Treasuries. Each is issued by a monetarily sovereign government. In practice, German Bunds have served as the eurozone’s risk-free anchor, with peripheral spreads quoted relative to Bunds. Japanese JGBs play the same role domestically. Cross-border investors face the additional layer of currency risk, which removes the risk-free label entirely from a foreign-currency perspective.

How did the 2011 US downgrade affect the risk-free concept?

The S&P downgrade from AAA to AA+ in August 2011 was largely symbolic for markets. Treasury yields actually fell in the days following the announcement as investors fled to safety — including, paradoxically, to Treasuries. The episode demonstrated that market practice trumps formal ratings: as long as Treasuries are the deepest, most liquid debt market in the world and the dollar remains the global reserve currency, they retain their risk-free status in practice regardless of formal ratings.

Last updated — 5 May 2026