# Real Interest Rates: Inflation, TIPS, and Valuation

Real interest rates adjust nominal rates for inflation; sound analysis distinguishes expected from realized inflation and market real yields from pure expectations.

Canonical: https://wiki.fcontext.com/stocks/real-interest-rate/
Fact checked: 2026-07-21

> For educational purposes only; not investment advice.

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## Direct answer

An **ex ante real interest rate** adjusts a nominal rate for expected inflation over the same horizon. The approximation is `real rate ≈ nominal rate - expected inflation`; the exact Fisher relation is `real rate = (1 + nominal rate) / (1 + expected inflation) - 1`. An **ex post real rate** substitutes realized inflation and is known only afterward. Maturity, currency, credit risk, compounding, and tax treatment must match before rates are compared.

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## How real rates are observed

Treasury Inflation-Protected Securities (TIPS) adjust principal using CPI-U, and their fixed coupon is applied to adjusted principal. A quoted TIPS yield is therefore a useful market real yield, but it is not a pure policy rate: liquidity, taxes, indexation lag, the deflation floor, and market positioning can affect it.

Same-maturity nominal Treasury yield minus TIPS real yield is the approximate **breakeven inflation rate**. It includes expected inflation plus inflation-risk and liquidity premiums, so it is not an exact inflation forecast.

Real rates influence saving, borrowing, investment, and the present value of inflation-adjusted cash flows. Nominal cash flows require nominal discount rates. Stock prices also reflect expected earnings and equity risk premiums, so a higher real yield does not mechanically imply a particular stock return.

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## Calculation example

With a `5%` nominal rate and `3%` expected inflation, the shortcut gives `2%`; the exact result is `(1.05 / 1.03) - 1 = 1.9417%`. If realized inflation is `4.5%`, the ex post real return is only `(1.05 / 1.045) - 1 = 0.4785%`.

If a 10-year nominal Treasury yields `4.2%` and a comparable TIPS yields `1.7%`, breakeven inflation is approximately `2.5%`, not a guaranteed forecast. A real `$100` cash flow due in 10 years is worth about `$84.49` at a `1.7%` real discount rate and `$80.44` at `2.2%`, before any cash-flow change.

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## Review checklist

- Match observation date, maturity, compounding, currency, and credit quality.
- Separate expected inflation from current or subsequently realized CPI.
- Treat corporate yield minus inflation as credit-bearing, not a risk-free real rate.
- Account for TIPS liquidity, taxes, indexation lag, accrued principal, and deflation floor.
- Decompose breakevens conceptually into expectations, risk premium, and liquidity effects.
- Discount real cash flows with real rates and nominal cash flows with nominal rates.
- Ask why rates changed; growth, inflation, policy, and risk premiums may move together.

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## Common misconceptions

- “Real rate always equals nominal rate minus current CPI.” Ex ante analysis uses expected inflation of matching horizon.
- “TIPS yield is a pure Federal Reserve policy signal.” Market and security-specific effects remain.
- “Breakeven inflation is the market's exact forecast.” It contains premiums and technical distortions.
- “A negative real rate guarantees asset gains.” Returns still depend on cash flows, valuation, and risk.
- “Higher real rates always lower every stock.” Earnings expectations and risk premiums can offset discount-rate effects.

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## Related topics

- [CPI and Inflation](/stocks/cpi-inflation/)
- [Interest Rate Impact](/stocks/interest-rate-impact/)
- [Discount Rate](/stocks/discount-rate/)

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## Authoritative sources

- [Treasury Inflation-Protected Securities](https://treasurydirect.gov/marketable-securities/tips/) - U.S. Treasury
- [Selected Interest Rates (H.15)](https://www.federalreserve.gov/releases/h15/) - Federal Reserve
- [TIPS from TIPS](https://www.federalreserve.gov/econres/notes/feds-notes/tips-from-tips-update-and-discussions-20190521.html) - Federal Reserve