Question 12.4: Calculating the Geometric Average Return Calculate the geome...

Calculating the Geometric Average Return 

Calculate the geometric average return for S&P 500 large-cap stocks for the first five years in Table 12.1, 1926–1930.

First, convert percentages to decimal returns, add 1, and then calculate their product:

Table 12.1, Year-to-Year Total Returns: 1926–2010.

Consumer
Price
Index
.U.S
Treasury
Bills
Long-Term -Large
Company Stocks
Year Consumer
Price
Index
.U.S
Treasury
Bills
Long-Term
Government
Bonds
Large
Company-
Stocks
Year
6.2 6.9 5.63- 8.43- 1969 1.12%- 3.30% 5.69% 13.75% 1926
5.57 6.5 18.92 3.94 1970 2.26- 3.15 6.58 35.7 1927
3.27 4.36 11.24 14.3 1971 1.16- 4.05 1.15 45.08 1928
3.41 4.23 2.39 18.99 1972 58. 4.47 4.39 8.8- 1929
8.71 7.29 3.3 14.69- 1973 6.40- 2.27 4.47 25.13- 1930
12.34 7.99 4 26.47- 1974 9.32- 1.15 2.15- 43.6- 1931
6.94 5.87 5.52 37.23 1975 10.27- 88. 8.51 8.75- 1932
4.86 5.07 15.56 23.93 1976 76. 52. 1.92 52.95 1933
6.7 5.45 0.38 7.16- 1977 1.52 27. 7.59 2.31- 1934
9.02 7.64 1.26- 6.57 1978 2.99 17. 4.2 46.79 1935
13.29 10.56 1.26 18.61 1979 1.45 17. 5.13 32.49 1936
12.52 12.1 2.48- 32.5 1980 2.86 27. 1.44 -35.45 1937
8.92 14.6 4.04 4.92- 1981 2.78- 06. 4.21 31.63 1938
3.83 10.94 44.28 21.55 1982 0.0 04. 3.84 1.43- 1939
3.79 8.99 1.29 22.56 1983 71. 04. 5.7 10.36- 1940
3.95 9.9 15.29 6.27 1984 9.93 14. 47. 12.02- 1941
3.8 7.71 32.27 31.73 1985 9.03 34. 1.8 20.75 1942
1.1 6.09 22.39 18.67 1986 2.96 38. 2.01 25.38 1943
4.43 5.88 3.03- 5.25 1987 2.3 38. 2.27 19.49 1944
4.42 6.94 6.84 16.61 1988 2.25 38. 5.29 36.21 1945
4.65 8.44 18.54 31.69 1989 18.13 38. 54. 8.42- 1946
6.11 7.69 7.74 3.1- 1990 8.84 62. 1.02- 5.05 1947
3.06 5.43 19.36 30.46 1991 2.99 1.06 2.66 4.99 1948
2.9 3.48 7.34 7.62 1992 2.07- 1.12 4.58 17.81 1949
2.75 3.03 13.06 10.08 1993 5.93 1.22 98.- 30.05 1950
2.67 4.39 7.32- 1.32 1994 6 1.56 20.- 23.79 1951
2.54 5.61 25.94 37.58 1995 75. 1.75 2.43 18.39 1952
3.32 5.14 0.13 22.96 1996 75. 1.87 2.28 1.07- 1953
1.7 5.19 12.02 33.36 1997 74.- 93. 3.08 52.23 1954
1.61 4.86 14.45 28.58 1998 37. 1.80 73.- 31.62 1955
2.68 4.8 7.51- 21.04 1999 2.99 2.66 1.72- 6.91 1956
3.39 5.98 17.22 9.1- 2000 2.9 3.28 6.82 10.5- 1957
1.55 3.33 5.51 11.89- 2001 1.76 1.71 1.72- 43.57 1958
2.38 1.61 15.15 22.1- 2002 1.73 3.48 2.02- 12.01 1959
1.88 94. 2.01 28.89 2003 1.36 2.81 11.21 47. 1960
3.26 1.14 8.12 10.88 2004 67. 2.40 2.20 26.84 1961
3.42 2.79 6.89 4.91 2005 1.33 2.82 5.72 -8.75 1962
2.54 4.97 28. 15.79 2006 1.64 3.23 1.79 22.7 1963
4.08 4.52 10.85 5.49 2007 97. 3.62 3.71 16.43 1964
09. 1.24 41.78 37- 2008 1.92 4.06 93. 12.38 1965
2.72 15. 25.61- 26.46 2009 3.46 4.94 5.12 10.06- 1966
1.5 14. 7.73 15.06 2010 3.04 4.39 2.86- 23.98 1967
4.72 5.49 2.25 11.03 1968
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First, convert percentages to decimal returns, add 1, and then calculate their product:

Product S&P 500 Returns
1.1375 13.75
×1.3570 35.7
×1.4508 45.08
×.9120 -8.80
×.7487 -25.13

1.5291

Notice that the number 1.5291 is what our investment is worth after five years if we started with a $1 investment. The geometric average return is then calculated as follows:

Geometric average return = 1.5291^{1/5} -1=.0887, or 8.87%

Thus, the geometric average return is about 8.87 percent in this example. Here is a tip: If you are using a financial calculator, you can put $1 in as the present value, $1.5291 as the future value, and 5 as the number of periods. Then, solve for the unknown rate. You should  get the same answer we did.

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