31 Month Growth Rate

This chart shows the 31 month growth rate of the S&P 500, using monthly average data. We have spliced the Cowles Commission average on so that the can show over a century of data (raw data starts in 1871). The growth is based on price appreciation only, dividends and inflation are not accounted for.

Another extremely high growth rate. July's 31 month growth rate (31.60%, annualized) ranked 5^th out of 1489 monthly readings. In other words, it hasn't been sustainable in the past 120 years.

Note: The four months with higher 31 month growth rates were 9/29, 8/29, 7/29 and 4/56 (in descending order).

31 Month Constant Dollar Growth Rate

This chart shows the 31 month growth rate of the contstant dollar S&P 500, using monthly average data. We have spliced the Cowles Commission average on so that the can show over a century of data (raw data starts in 1871). The constant dollar S&P 500 is adjusted for inflation by dividing by the Consumer Price Index. The most recent value of CPI is carried forward (since CPI is released after the fact). Prior to 1913, annual CPI figures are interpolated to monthly values. The growth is based on price appreciation only, dividends are not accounted for.

The July 1997 constant dollar growth rate was 28.07% (annualized). That's 22^nd out of 1489. So only 98.5% of the constant dollar growth rates in history were lower than this one.

Note: Of the 21 higher readings, 12 were in 1928-9, 4 were in 1956, 4 were in 1880-1 and one was in 1935.

31 Month Summary

Stock market growth (31 month basis) has reached an extreme level, even after adjusting for inflation. 1929 provides the only example of a stock market that sustained this level of growth — but only for three months (nominal) and twelve months (inflation adjusted). Applying the lessons of history, we can say that 31 month growth rates are very near a significant peak.

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