Finance & Money · 内部收益率（IRR） · Updated 2026-10-25
What Is Internal Rate of Return (IRR)?
Definition
IRR is the discount rate that sets NPV to zero — the true annualized return for any mix of inflows and outflows. No closed form; solved iteratively (Excel’s IRR function).
Formula
Σ CF_t / (1+IRR)^t = 0
Worked Example
A 12-month 6% flat-fee installment plan has a true IRR near 11.5% APR because principal is repaid monthly.
Common Misconception
"Total return / total invested = annualized" - true only for a single lump-sum in and out; multiple cash flows require IRR (money-weighted return), otherwise DCA and installment scenarios are wildly off.
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