What If You Invested $100 a Month in the S&P 500 Since 2005?
Investing $100 a month in the S&P 500 from Jan 2005 to Oct 2026 would have turned $26,200 into about $133,867, a gain of $107,667 and a money-weighted annual return of 13.1%. Dividends are reinvested.
- Invested
- $26,200
- Value today
- $133,867
- Gain
- +$107,667
- Annual return
- 13.1%
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 2005. Money went in 262 times, and the total grew to 5.1 times what was invested.
| Year | Invested | Portfolio value | Gain or loss |
|---|---|---|---|
| 2005 | $1,200 | $1,254 | +$54 |
| 2006 | $2,400 | $2,772 | +$372 |
| 2007 | $3,600 | $4,120 | +$520 |
| 2008 | $4,800 | $3,493 | −$1,307 |
| 2009 | $6,000 | $5,889 | −$111 |
| 2010 | $7,200 | $8,142 | +$942 |
| 2011 | $8,400 | $9,490 | +$1,090 |
| 2012 | $9,600 | $12,272 | +$2,672 |
| 2013 | $10,800 | $17,631 | +$6,831 |
| 2014 | $12,000 | $21,303 | +$9,303 |
| 2015 | $13,200 | $22,775 | +$9,575 |
| 2016 | $14,400 | $26,812 | +$12,412 |
| 2017 | $15,600 | $33,970 | +$18,370 |
| 2018 | $16,800 | $33,524 | +$16,724 |
| 2019 | $18,000 | $45,357 | +$27,357 |
| 2020 | $19,200 | $55,115 | +$35,915 |
| 2021 | $20,400 | $72,330 | +$51,930 |
| 2022 | $21,600 | $60,310 | +$38,710 |
| 2023 | $22,800 | $77,460 | +$54,660 |
| 2024 | $24,000 | $98,069 | +$74,069 |
| 2025 | $25,200 | $116,787 | +$91,587 |
| Oct 2026 (latest) | $26,200 | $133,867 | +$107,667 |
The hardest moment to keep going
The biggest fall in the portfolio's value came between May 2008 and Feb 2009, when it dropped 32%, from $4,487 to $3,033, 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 $26,200 into the S&P 500 in Jan 2005 would be worth $247,762 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 $26,200, 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.