Two separate calculations
The custom scenario converts your annual effective return R to a period rate (1 + R)^(1/m) − 1, where m is 12, 4 or 1. Each period first earns that return, then receives the contribution. Monthly and yearly settings therefore use the same annual-return convention. A constant return is an assumption, not a prediction.
Historical purchase timing
The replay requests the chosen number of calendar years ending on the UTC retrieval date. It buys initial units at the first available close on or after the start date. Contributions are scheduled monthly, quarterly or yearly from that date, with month-end dates clamped to valid calendar days. A weekend or holiday uses the next returned observation within seven calendar days.
A missing scheduled observation beyond that tolerance makes the result unavailable. The ending observation must be within seven days of the requested end. Contributions scheduled after the last available close are not yet invested. The actual start and end dates appear above the chart. The replay never repeats the final close to fabricate additional years.
Prices, units and exclusions
Historical mode uses the provider’s close field from FMP historical price data. Fractional units are modeled. No separate dividends, split ledger, reinvestment, fees, tax, inflation or currency conversion is applied. Check the provider’s adjustment basis before interpreting units as historical share holdings. The page does not fetch a current quote for final valuation; it uses the last included historical close.
What dollar-cost averaging means
Investor.gov defines regular equal contributions regardless of market movements. Fixed cash purchases acquire more units at lower prices and fewer at higher prices. This does not guarantee profit, beat a lump-sum purchase or prevent concentration risk. This page models contributions; it does not automate investments.
Frequently asked questions
Is the projection a forecast?
No. It applies one constant annual effective return, converted to the selected contribution frequency. Actual returns vary, and losses are possible. Contributions are added at each period end.
How does the historical replay choose purchase dates?
It starts the requested number of calendar years before the retrieval date. Initial and periodic purchases use the first returned close on or after each scheduled date, within seven calendar days. Missing coverage stops the replay instead of repeating the last price.
Does the replay include dividends, fees or taxes?
No separate dividends, reinvestment, tax, fees, inflation or corporate-action ledger is modeled. It uses provider closing-price observations as a price series. Units are illustrative and depend on the provider adjustment basis; verify that basis before interpreting them as shares.
Should I add 1–2% for dividends?
No universal dividend adjustment is valid. Dividend yields, payment dates, reinvestment and withholding vary. Use a separately justified total-return assumption or a verified total-return series.
Does regular investing guarantee a lower cost or profit?
No. Fixed cash contributions buy more units at lower prices, but that does not guarantee a lower cost than a lump-sum investment or protect against sustained losses.
Educational scenarios only, not investment advice.