What if you had put money into a stock or ETF 10 years ago, once or every month? Pick the ticker and the amount. The simulator replays real monthly prices with dividends reinvested, and draws a second ticker on the same chart so you can see who actually won.
Moves to the first month with data for both tickers.
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Set to 0 for a one-time investment.
Use it for long periods or big winners.
Result
Worth today—
Total put in
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Gain
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If it all went in on day one
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Price return per year
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Worst drop from a peak
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Same plan in —
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——Money put in
Monthly closing prices adjusted for splits and dividends (Yahoo Finance), data through 2026-11. Each monthly amount buys at that month's close. Taxes and fees are not included.
How the what-if calculator works
On the start month your starting amount buys shares at that month's closing price. Every month after that, the monthly amount buys more shares at the new price. Dividends are already folded into the price history, so they are treated as reinvested. Your value on any date is simply the shares you own times that month's price.
If it all went in on day one takes the same total you put in and invests it all on the start month. Markets have gone up more often than down, so the lump sum usually ends higher. Monthly investing tends to win when the start month sits right before a big fall, such as late 2007 or late 1999. Try those dates and watch the lines cross.
Worst drop from a peak is the largest fall in the ticker's price from a high to a later low inside your period. It tells you how much pain you would have had to sit through to get the final number.
Things to keep in mind
Monthly prices hide moves inside a month, so the real worst drop was usually a bit deeper.
Leveraged ETFs such as TQQQ can look spectacular in rising periods and lose most of their value in falls. Compare TQQQ with QQQ from 2021-11 to see it.
A stock that did well in the past was picked because it did well. That is hindsight, not a forecast.