With the recent melt down in global markets, it would be prudent to look back at historical data on the US market to see where we stand. To do this I look at major tops and bottoms in the S&P500 obtained from weekly historical data from Yahoo Finance since 1950. The first table below shows major tops and bottoms in the S and P 500 relative to the average and standard deviation:
Table 1: S&P 500 Tops/Bottoms, Average & Standard Deviation over Time
| Date | S&P500 Top / Bottom | Average | Standard Deviation |
| November 25, 1968 | 108.37 | 55.37 | 24.92 |
| May 18, 1970 | 72.25 | 58.26 | 26.21 |
| January 2, 1973 | 119.87 | 62.90 | 28.12 |
| September 30, 1974 | 62.34 | 65.38 | 28.78 |
| December 22, 1980 | 136.57 | 72.26 | 29.69 |
| August 2, 1982 | 103.71 | 74.74 | 31.00 |
| August 17, 1987 | 335.9 | 90.93 | 53.55 |
| 30-Nov-87 | 223.92 | 92.37 | 55.95 |
| 13-Jul-98 | 1186.75 | 181.77 | 203.72 |
| 31-Aug-98 | 973.89 | 184.22 | 208.73 |
| 20-Mar-00 | 1527.46 | 218.64 | 282.52 |
| 2-Apr-01 | 1128.43 | 242.13 | 324.34 |
| 14-May-01 | 1291.96 | 244.38 | 327.45 |
| 10-Sep-01 | 965.8 | 250.33 | 334.93 |
| 11-Mar-02 | 1166.16 | 258.34 | 343.62 |
| 30-Sep-02 | 800.58 | 266.00 | 349.94 |
| 8-Oct-07 | 1561.8 | 346.50 | 427.52 |
| 2-Mar-09 | 683.38 | 366.81 | 443.71 |
| 19-Apr-10 | 1217.28 | 379.11 | 448.71 |
| 28-Jun-10 | 1022.58 | 381.39 | 449.82 |
| 2-May-11 | 1340.2 | 392.94 | 457.43 |
| 15-Aug-11 | 1123.53 | 397.09 | 460.40 |
| 13-Jul-15 | 2126.64 | 474.27 | 543.97 |
As can be seen in the table above on only one major bottom in 1974, the market tested it's long term average since 1950. We have not tested the average since 1974 for well over 40 years. The other interesting observation is that the standard deviation of the market has exceeded it's average since 1998 with the market way above its average. This coincides with the involvement of the FED in the market since 1998 post the Long Term Capital debacle and suggests that the risk in the market has increased significantly. The markets average since 1950 currently stands at about 475.
The next table shows the deviation from the average at major tops and bottoms and the return from highs to lows and lows to highs. The market in its early stages till about 1987 always peaked out at about 2 standard deviations above the average. Since 1987 the market has gotten as high as 5 standard deviations above its long term average. Bottoms tend to occur within 1.5 standard deviations from the average. Every key top at above 2 standard deviations from the mean produced a decline of at least 16%. The current market is the fourth most over extended market in history.
Table 2: No of Standard Deviations from the Average at Major S&P500 Tops/Bottoms and Subsequent Returns from Tops to Bottoms and Bottoms to Tops
| Date | No of Standard Deviations from Average | % Change |
| November 25, 1968 | 2.13 | -33% |
| May 18, 1970 | 0.53 | 66% |
| January 2, 1973 | 2.03 | -48% |
| September 30, 1974 | -0.11 | 119% |
| December 22, 1980 | 2.17 | -24% |
| August 2, 1982 | 0.93 | 224% |
| August 17, 1987 | 4.57 | -33% |
| 30-Nov-87 | 2.35 | 430% |
| 13-Jul-98 | 4.93 | -18% |
| 31-Aug-98 | 3.78 | 57% |
| 20-Mar-00 | 4.63 | -26% |
| 2-Apr-01 | 2.73 | 14% |
| 14-May-01 | 3.20 | -25% |
| 10-Sep-01 | 2.14 | 21% |
| 11-Mar-02 | 2.64 | -31% |
| 30-Sep-02 | 1.53 | 95% |
| 8-Oct-07 | 2.84 | -56% |
| 2-Mar-09 | 0.71 | 78% |
| 19-Apr-10 | 1.87 | -16% |
| 28-Jun-10 | 1.43 | 31% |
| 2-May-11 | 2.07 | -16% |
| 15-Aug-11 | 1.58 | 89% |
| 13-Jul-15 | 3.04 | ? |
Finally drilling down to tops and bottoms since 2000, the average top to bottom decline since 2000 is 28% while the average bottom to top return since 2000 is 55%.
So the question begs what does it mean for today's market? We have already started breaking down from over extended levels. The current market average is about 474 and standard deviation is 544. Here are some scenarios below:
Table 3: S&P500 Possible Scenarios
| Market Average (MA)+ Standard Deviation (SD) | S&P500 Level |
| MA | 474 |
| MA + 1 SD | 1018 |
| MA + 2 SD | 1562 |
| MA + 3 SD | 2106 |
The bottom line is folks we are historically over extended. We could now correct to at least 2 standard deviations above the long term average which is close to the 2008 highs near 1575 or to a standard deviation (#stdev) above the long term average as was the case at the 2008 lows near 1018 or to the long term average near 474 which we haven't revisited since 1974. Only time will tell.
