$100 a month in the S&P 500 since 2021
Investing $100 every month in an S&P 500 index fund from January 2021 to Sep 2026 added up to $6,900. With dividends reinvested, it would be worth about $11,146.
Real monthly S&P 500 data, updated monthly. How we calculate$100 a month into the S&P 500 since Jan 2021 is worth
You would have put in $6,900 over 69 monthly buys.
If you had invested the whole $6,900 in Jan 2021, it would be worth $15,037. S&P 500 monthly average prices, dividends reinvested (recent months use the last reported dividend, Jun 2023). Data through Sep 2026. One buy per month at that month's average price; no fees or taxes. Past returns do not predict future returns.
The result
That is 69 monthly buys. The balance ended at 1.6× the money put in, a money-weighted return of 17.0% a year. Without reinvesting dividends it would be $10,719, so dividends added $427.
Prices rose along the way, so the deposits are worth more in today's money than their face value: $6,900 of deposits equals about $7,615 in today's dollars. Even measured that way, the plan ended 1.5× ahead.
The hardest stretch: the balance fell 8% from its high around Apr 2025, during the 2025 tariff sell-off. Someone who kept buying through that drop bought shares cheaply, which is a large part of the final number.
| After | Put in | Worth |
|---|---|---|
| 5 years (2025) | $6,000 | $9,038 |
| Now (Sep 2026) | $6,900 | $11,146 |
How the balance grew, with dividends reinvested. No fees or taxes.
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Common questions
How much is $100 a month in the S&P 500 since 2021 worth today?
About $11,146 as of Sep 2026, from $6,900 invested, with dividends reinvested and no fees or taxes.
What was the yearly return?
17.0% a year, measured as a money-weighted return that accounts for when each monthly deposit went in.
What was the worst moment?
A 8% fall from the previous high around Apr 2025, during the 2025 tariff sell-off. The plan only reached today's value because the buying continued.
Will the next 6 years be the same?
Nobody knows. Past returns do not predict future returns, and the S&P 500 has had decade-long stretches with little gain.
Based on the S&P 500 monthly average level with dividends reinvested (an index fund before its small fee). Educational estimates, not investment advice. Past returns do not predict future returns.
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