What If You Invested $100 a Month in the S&P 500 Since 2008?
Investing $100 a month in the S&P 500 from Jan 2008 to Oct 2026 would have turned $22,600 into about $103,354, a gain of $80,754 and a money-weighted annual return of 14.3%. Dividends are reinvested.
- Invested
- $22,600
- Value today
- $103,354
- Gain
- +$80,754
- Annual return
- 14.3%
Year by year
The value of the portfolio at the end of each year, investing $100 a month at the start of every month from Jan 2008. Money went in 226 times, and the total grew to 4.6 times what was invested.
| Year | Invested | Portfolio value | Gain or loss |
|---|---|---|---|
| 2008 | $1,200 | $889 | −$311 |
| 2009 | $2,400 | $2,599 | +$199 |
| 2010 | $3,600 | $4,357 | +$757 |
| 2011 | $4,800 | $5,633 | +$833 |
| 2012 | $6,000 | $7,798 | +$1,798 |
| 2013 | $7,200 | $11,711 | +$4,511 |
| 2014 | $8,400 | $14,587 | +$6,187 |
| 2015 | $9,600 | $15,975 | +$6,375 |
| 2016 | $10,800 | $19,196 | +$8,396 |
| 2017 | $12,000 | $24,702 | +$12,702 |
| 2018 | $13,200 | $24,679 | +$11,479 |
| 2019 | $14,400 | $33,750 | +$19,350 |
| 2020 | $15,600 | $41,381 | +$25,781 |
| 2021 | $16,800 | $54,650 | +$37,850 |
| 2022 | $18,000 | $45,843 | +$27,843 |
| 2023 | $19,200 | $59,207 | +$40,007 |
| 2024 | $20,400 | $75,273 | +$54,873 |
| 2025 | $21,600 | $89,952 | +$68,352 |
| Oct 2026 (latest) | $22,600 | $103,354 | +$80,754 |
The hardest moment to keep going
The biggest fall in the portfolio's value came between Dec 2021 and Sep 2022, when it dropped 23%, from $54,650 to $42,340, even with new money going in every month. An investor who kept buying through that stretch got more shares for each $100, and those purchases are part of the result above.
Monthly investing vs other choices
- All at once: putting the same $22,600 into the S&P 500 in Jan 2008 would be worth $167,375 today. The lump sum did better because all of it was invested for the whole period, which is the usual result when prices rise. Most people invest from their income, so few have the whole amount at the start.
- Cash: keeping the money uninvested would leave exactly $22,600, worth less after inflation.
Annual return is the money-weighted return (IRR) of the monthly contributions. Prices are monthly closes from Yahoo Finance, updated each time the site is rebuilt. See the methodology. This is for education only and is not investment advice. Past performance does not guarantee future results.