If you invested $100 in the S&P 500 at the beginning of 2001, you would have about $119.73 at the end of 2011, assuming you reinvested all dividends. This is a return on investment of 19.73%, or 1.65% per year.
This lump-sum investment does not beat inflation during this period, for an inflation-adjusted return of -5.73% cumulatively, or -0.54% per year.
If you used dollar-cost averaging (monthly) instead of a lump-sum investment, you'd have $146.44.
The graph below shows the performance of $100 over time if invested in an S&P 500 index fund. The returns assume that all dividends are automatically reinvested.
The nominal return on investment of $100 is $19.73, or 19.73%. This means by 2011 you would have $119.73 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 2001 was 177.100 and the CPI in 2011 was 224.939.
The ratio between these CPIs describes how relative buying power of a dollar has changed over 10 years.
Adjusted for inflation, the $119.73 nominal end value of the original $100 investment would have a real return of roughly $-5.73 in 2001 dollars. This means the inflation-adjusted return is -5.73% as opposed to the original 19.73%.
The table below shows the full dataset pertaining to a $100 investment, including gains and losses over the 132-month period between 2001 and 2011.
Note that data shown is the monthly average closing price. Returns include dividends.
Year
Month
Return (%)
Amount ($)
CPI
2001
1
-2.14%
97.86
175.10
2001
2
-9.08%
88.98
175.80
2001
3
0.45%
89.38
176.20
2001
4
6.88%
95.53
176.90
2001
5
-2.39%
93.24
177.70
2001
6
-2.66%
90.76
178.00
2001
7
-2.05%
88.91
177.50
2001
8
-11.25%
78.91
177.50
2001
9
3.18%
81.42
178.30
2001
10
5.05%
85.53
177.70
2001
11
1.47%
86.79
177.40
2001
12
-0.30%
86.53
176.70
2002
1
-3.35%
83.63
177.10
2002
2
4.95%
87.76
177.80
2002
3
-3.51%
84.68
178.80
2002
4
-2.82%
82.29
179.80
2002
5
-5.92%
77.42
179.80
2002
6
-10.76%
69.09
179.90
2002
7
1.14%
69.88
180.10
2002
8
-4.76%
66.55
180.70
2002
9
-1.37%
65.64
181.00
2002
10
6.63%
69.99
181.30
2002
11
-1.04%
69.27
181.30
2002
12
-0.22%
69.11
180.90
2003
1
-6.41%
64.68
181.70
2003
2
1.31%
65.52
183.10
2003
3
5.29%
68.99
184.20
2003
4
5.31%
72.65
183.80
2003
5
5.70%
76.80
183.50
2003
6
0.60%
77.26
183.70
2003
7
-0.17%
77.13
183.90
2003
8
3.16%
79.56
184.60
2003
9
2.03%
81.18
185.20
2003
10
1.21%
82.16
185.00
2003
11
3.06%
84.68
184.50
2003
12
4.93%
88.86
184.30
2004
1
1.09%
89.82
185.20
2004
2
-1.57%
88.42
186.20
2004
3
0.97%
89.27
187.40
2004
4
-2.56%
86.98
188.00
2004
5
2.86%
89.47
189.10
2004
6
-2.24%
87.47
189.70
2004
7
-1.39%
86.25
189.40
2004
8
2.78%
88.65
189.50
2004
9
0.10%
88.74
189.90
2004
10
4.77%
92.98
190.90
2004
11
2.73%
95.52
191.00
2004
12
-1.35%
94.23
190.30
2005
1
1.68%
95.81
190.70
2005
2
-0.26%
95.57
191.80
2005
3
-2.41%
93.26
193.30
2005
4
1.34%
94.51
194.60
2005
5
2.18%
96.57
194.40
2005
6
1.81%
98.32
194.50
2005
7
0.31%
98.62
195.40
2005
8
0.28%
98.90
196.40
2005
9
-2.62%
96.30
198.80
2005
10
3.96%
100.12
199.20
2005
11
2.14%
102.26
197.60
2005
12
1.47%
103.76
196.80
2006
1
-0.02%
103.75
198.30
2006
2
1.49%
105.29
198.70
2006
3
0.80%
106.13
199.80
2006
4
-0.79%
105.29
201.50
2006
5
-2.71%
102.45
202.50
2006
6
0.72%
103.18
202.90
2006
7
2.29%
105.55
203.50
2006
8
2.53%
108.22
203.90
2006
9
3.62%
112.13
202.90
2006
10
2.00%
114.38
201.80
2006
11
2.15%
116.83
201.50
2006
12
0.69%
117.64
201.80
2007
1
1.60%
119.52
202.42
2007
2
-2.47%
116.56
203.50
2007
3
4.18%
121.44
205.35
2007
4
3.39%
125.56
206.69
2007
5
0.34%
125.99
207.95
2007
6
0.57%
126.71
208.35
2007
7
-4.20%
121.39
208.30
2007
8
3.07%
125.12
207.92
2007
9
2.99%
128.87
208.49
2007
10
-4.81%
122.67
208.94
2007
11
1.24%
124.19
210.18
2007
12
-6.64%
115.95
210.04
2008
1
-1.56%
114.14
211.08
2008
2
-2.63%
111.14
211.69
2008
3
4.24%
115.86
213.53
2008
4
2.56%
118.82
214.82
2008
5
-4.25%
113.78
216.63
2008
6
-6.08%
106.86
218.82
2008
7
2.11%
109.12
219.96
2008
8
-4.85%
103.83
219.09
2008
9
-20.19%
82.86
218.78
2008
10
-8.61%
75.73
216.57
2008
11
-0.35%
75.47
212.43
2008
12
-1.10%
74.64
210.23
2009
1
-6.70%
69.64
211.14
2009
2
-5.69%
65.68
212.19
2009
3
12.32%
73.77
212.71
2009
4
6.66%
78.68
213.24
2009
5
2.87%
80.94
213.86
2009
6
1.28%
81.97
215.69
2009
7
8.12%
88.63
215.35
2009
8
3.65%
91.86
215.83
2009
9
2.40%
94.07
215.97
2009
10
2.09%
96.04
216.18
2009
11
2.23%
98.18
216.33
2009
12
1.36%
99.51
215.95
2010
1
-2.90%
96.63
216.69
2010
2
5.94%
102.37
216.74
2010
3
4.09%
106.55
217.63
2010
4
-5.88%
100.29
218.01
2010
5
-3.54%
96.73
218.18
2010
6
-0.16%
96.58
217.97
2010
7
0.86%
97.41
218.01
2010
8
3.37%
100.70
218.31
2010
9
4.58%
105.31
218.44
2010
10
2.49%
107.93
218.71
2010
11
3.71%
111.94
218.80
2010
12
3.46%
115.81
219.18
2011
1
3.15%
119.46
220.22
2011
2
-1.11%
118.13
221.31
2011
3
2.22%
120.76
223.47
2011
4
0.66%
121.55
224.91
2011
5
-3.66%
117.10
225.96
2011
6
3.10%
120.73
225.72
2011
7
-10.40%
108.18
225.92
2011
8
-0.79%
107.32
226.55
2011
9
3.02%
110.56
226.89
2011
10
1.77%
112.52
226.42
2011
11
1.55%
114.27
226.23
2011
12
4.78%
119.73
225.67
Click to show 114 more rows
Remember, returns are based on the average closing price across the entire month. Some losses are offset by dividend returns.
Dollar-cost averaging
Dollar-cost averaging is an alternative to investing the full lump-sum of $100.00 up-front. Instead, the capital is invested over a period of time.
Consider a strategy in which $100.00 was invested in the S&P 500 over a period of no more than 24 months beginning in 2001. This would result in a final amount of $146.44, including dividend reinvestments. In this particular case, dollar-cost average returns are greater than the returns of a lump-sum investment (which ends with $119.73).
Year
Month
Contribution ($)
Amount ($)
2001
1
4.16
4.07
2001
2
4.16
7.48
2001
3
4.16
11.68
2001
4
4.16
16.93
2001
5
4.16
20.58
2001
6
4.16
24.08
2001
7
4.16
27.66
2001
8
4.16
28.23
2001
9
4.16
33.42
2001
10
4.16
39.47
2001
11
4.16
44.27
2001
12
4.16
48.28
2002
1
4.16
50.68
2002
2
4.16
57.54
2002
3
4.16
59.53
2002
4
4.16
61.89
2002
5
4.16
62.13
2002
6
4.16
59.15
2002
7
4.16
64.03
2002
8
4.16
64.94
2002
9
4.16
68.15
2002
10
4.16
77.09
2002
11
4.16
80.41
2002
12
4.32
84.53
2003
1
-
79.11
2003
2
-
80.14
2003
3
-
84.38
2003
4
-
88.86
2003
5
-
93.93
2003
6
-
94.49
2003
7
-
94.33
2003
8
-
97.31
2003
9
-
99.29
2003
10
-
100.49
2003
11
-
103.57
2003
12
-
108.68
2004
1
-
109.86
2004
2
-
108.14
2004
3
-
109.19
2004
4
-
106.39
2004
5
-
109.43
2004
6
-
106.98
2004
7
-
105.49
2004
8
-
108.43
2004
9
-
108.54
2004
10
-
113.72
2004
11
-
116.82
2004
12
-
115.25
2005
1
-
117.19
2005
2
-
116.89
2005
3
-
114.07
2005
4
-
115.59
2005
5
-
118.12
2005
6
-
120.25
2005
7
-
120.62
2005
8
-
120.96
2005
9
-
117.79
2005
10
-
122.45
2005
11
-
125.08
2005
12
-
126.91
2006
1
-
126.89
2006
2
-
128.78
2006
3
-
129.81
2006
4
-
128.78
2006
5
-
125.30
2006
6
-
126.20
2006
7
-
129.09
2006
8
-
132.36
2006
9
-
137.15
2006
10
-
139.89
2006
11
-
142.90
2006
12
-
143.89
2007
1
-
146.19
2007
2
-
142.57
2007
3
-
148.53
2007
4
-
153.57
2007
5
-
154.10
2007
6
-
154.98
2007
7
-
148.47
2007
8
-
153.04
2007
9
-
157.61
2007
10
-
150.04
2007
11
-
151.90
2007
12
-
141.82
2008
1
-
139.60
2008
2
-
135.93
2008
3
-
141.70
2008
4
-
145.33
2008
5
-
139.16
2008
6
-
130.70
2008
7
-
133.46
2008
8
-
126.99
2008
9
-
101.35
2008
10
-
92.63
2008
11
-
92.30
2008
12
-
91.29
2009
1
-
85.17
2009
2
-
80.33
2009
3
-
90.22
2009
4
-
96.23
2009
5
-
98.99
2009
6
-
100.26
2009
7
-
108.40
2009
8
-
112.36
2009
9
-
115.06
2009
10
-
117.47
2009
11
-
120.08
2009
12
-
121.71
2010
1
-
118.18
2010
2
-
125.21
2010
3
-
130.33
2010
4
-
122.66
2010
5
-
118.31
2010
6
-
118.12
2010
7
-
119.14
2010
8
-
123.16
2010
9
-
128.80
2010
10
-
132.01
2010
11
-
136.91
2010
12
-
141.65
2011
1
-
146.11
2011
2
-
144.49
2011
3
-
147.70
2011
4
-
148.67
2011
5
-
143.22
2011
6
-
147.67
2011
7
-
132.31
2011
8
-
131.26
2011
9
-
135.23
2011
10
-
137.62
2011
11
-
139.76
2011
12
-
146.44
Click to show 114 more rows
Data Sources
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.
About the author
Ian Webster is an engineer and data expert based in San Mateo, California. He has worked for Google, NASA, and consulted for governments around the world on data pipelines and data analysis. Disappointed by the lack of clear resources on the impacts of inflation on economic indicators, Ian believes this website serves as a valuable public tool. Ian earned his degree in Computer Science from Dartmouth College.
