How it works & FAQ
How 10-eok turns real historical data into a result
Calculation steps at a glance
- Fetch the selected ticker's daily adjusted closing prices.
- On the chosen buy day each month (moving to the next trading day if the market was closed), buy shares with the specified dollar amount at that day's actual closing price.
- For every trading day, calculate your portfolio value as shares held × that day's price.
- Find the first day the portfolio value crosses $1,000,000, and show how long that took.
Data sources
- Price: Yahoo Finance daily adjusted close. Dividend reinvestment, stock splits, and expense ratios are already reflected.
- Inflation index: U.S. Consumer Price Index (FRED, CPIAUCSL). Used for the "increase contributions with inflation" option.
- Data refreshes automatically once a day.
Assumptions and simplifications
- Dividends are assumed to be reinvested (using adjusted close prices).
- Taxes are not factored in by default (results are shown at market value, on an unrealized basis). Tax rules vary widely by country and situation, so consult a tax professional for your own case.
- Trading fees and bid/ask spreads are excluded for simplicity.
- Shares are assumed to be purchasable in fractional amounts (a model simplification).
Frequently asked questions
Does the result guarantee future returns?
No. Every result is simply a record of "what would have happened if you'd done this in the past." Past returns do not guarantee future results.
Why start with QLD?
It has a long price history (since 2006) and enough volatility to clearly show what dollar-cost averaging does. More tickers are being added over time.
What does "Annualized" mean?
It's the compound annual growth rate (CAGR) — roughly how many percent your balance grew per year, on average, over the holding period.
What's the difference between dividend reinvestment ON and OFF?
ON (the default) uses total return — dividends are bought back into more shares (adjusted close prices). OFF uses price return only, excluding dividends, so it comes out lower than the real result. The gap is bigger for tickers with higher dividend yields.
What does "increase contributions with inflation" do?
Instead of investing the same amount every month, this scenario raises your monthly contribution each year in line with the U.S. Consumer Price Index (CPI). It's a more realistic assumption if your actual income also rises roughly with inflation.
Does this account for taxes?
No — taxes aren't factored in by default. Tax treatment varies a lot by country, account type, and individual situation, so please consult a tax professional for your own case.
Should I actually invest this way?
This is an informational tool, not investment advice or a solicitation. Make sure you fully understand the risks of leveraged products, and make your own investment decisions.
You can read more about how the calculation logic works in the guides.