If you invested $10000 in the S&P 500 at the beginning of 1975, you would have about $22,409.93 at the end of 1981, assuming you reinvested all dividends. This is a return on investment of 124.10%, or **12.22% per year**.

If you used dollar-cost averaging (monthly) instead of a lump-sum investment, you'd have $16,765.43.

This investment result beats inflation during this period for an inflation-adjusted return of about 32.64% cumulatively, or **4.12% per year**.

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The graph below shows the performance of $10000 over time if invested in an S&P 500 index fund. The returns assume that all dividends are automatically reinvested.

This chart shows the rate of gains and loss by month, including dividends:

The *nominal* return on investment of $10000 is $12,409.93, or 124.10%. This means by 1981 you would have $22,409.93 in your pocket.

However, it's important to take into account the effect of inflation when considering an investment and especially a long-term investment. You can convert S&P returns to their *real* (inflation-adjusted) value using an inflation calculation based on the U.S. Bureau of Labor Statistics Consumer Price Index (CPI).

In the case of the returns described above, the CPI in 1975 was 53.800 and the CPI in 1981 was 90.900.

The ratio between these CPIs describes how relative buying power of a dollar has changed over 6 years.

Adjusted for inflation, the $22,409.93 *nominal* end value of the original $10000 investment would have a *real* value of roughly **$3,263.53** in 1975 dollars. This means the inflation-adjusted return is **32.64%** as opposed to the original 124.10%.

For more information on inflation, see our U.S. inflation calculator for 1975.

The table below shows the full dataset pertaining to a $10000 investment, including gains and losses over the 84-month period between 1975 and 1981.

Note that data shown is the *monthly average closing price*. Returns include dividends.

Dollar-cost averaging is an alternative to investing the full lump-sum of $10,000.00 up-front. Instead, the capital is invested over a period of time.

Consider a strategy in which $10,000.00 was invested in the S&P 500 over a period of no more than 24 months beginning in 1975. This would result in a final amount of $16,765.43, including dividend reinvestments. In this particular case, dollar-cost average returns are **less than** the returns of a lump-sum investment (which ends with $22,409.93).

The information on this page is derived from Robert Shiller's book, Irrational Exuberance and the accompanying dataset, as well as the U.S. Bureau of Labor Statistics' monthly CPI logs.

Note that S&P index value for the current quarter is based on a moving average of closing prices, per Robert Shiller's methodology. The inflation data used is based on annual CPI averages.

Start Value
Average monthly close |
$72.56 |

End Value
Average monthly close |
$133.00 |

Change in price |
+83.30%
+10.63% / yr |

Change incl. dividends |
+124.10%
+12.22% / yr |

Change incl. dividends, inflation-adjusted |
+32.64%
+4.12% / yr |

Final amount, nominal ($10000 base) |
$22,409.93 |

Final amount, inflation-adjusted ($10000 base) |
$13,263.53 |