Compounding, Effective Rates, and Reinvestment

Investment terms for compounding, effective rates, reinvestment assumptions, and doubling-time rules.

Compounding, Effective Rates, and Reinvestment terms explain how investment results are measured, compared, annualized, compounded, distributed, or translated into yield language.

Use this branch when the question depends on the exact return formula, time period, reinvestment assumption, fee treatment, tax treatment, or income-versus-price return split.

Key Terms in This Branch

TermUse it for
CompoundingApplies each period’s return, charge, and cash flow to an updated balance.
Effective Interest RateDistinguishes annual compounding conversion from the accounting yield used for amortized cost.
Effective YieldConverts periodic compounding to an annual yield while distinguishing bond, deposit, fund, and realized-return conventions.
Reinvestment RateMeasures or assumes the return earned on coupons, distributions, principal repayments, or other interim cash flows.
Rule of 69.3Estimates doubling time under continuous compounding by dividing 69.3 by the percentage rate.

What to Check

Check the formula, measurement period, compounding convention, cash-flow timing, reinvestment assumption, fees, taxes, currency, and whether the result is historical, expected, quoted, or realized.

Common Mistakes

  • Comparing returns from different periods or compounding conventions.
  • Treating quoted yield or expected return as the same as realized performance.
  • Ignoring fees, taxes, currency, reinvestment, and cash-flow timing.
  • Mixing income return, price return, and total return without labeling each measure.

This page is educational and does not recommend a specific investment strategy, security, tax treatment, or account choice.

In this section

Choose a subsection first. Deeper term pages live inside each subsection, which keeps large topic hubs readable.

Compounding

Compounding applies each period's return to an updated balance, with frequency, cash flows, volatility, fees, and debt terms shaping the result.

Effective Interest Rate

Effective interest rate can mean an annual compounding conversion or the accounting yield used to calculate interest and amortized cost.

Effective Yield

Effective yield usually annualizes compounding, but the label varies across deposits, bonds, and funds. Learn the formula, example, and limitations.

Reinvestment Rate

The reinvestment rate is earned or assumed on interim cash flows and affects terminal wealth, while differing from the original coupon rate or quoted yield.

Rule of 69.3

The Rule of 69.3 estimates doubling time from a constant continuously compounded rate and differs from shortcuts used for periodic compounding.

Browse Investing