rdemyan -- outstanding! Thank you for the effort.
Quote from rdemyan:
Okay, here's some more results from the data. These results I would venture to say are 'hard' in the sense that they are not subject to any bias or interpretation on my part (other than the ranges I selected to look at).
1) 110 expiration-to-expiration periods are included starting from October 20, 1995 through December 17, 2004
2) Of those 110 periods, the SPX saw an increase in 61 of those periods (that is, the SPX was higher at the end of the period than at the beginning of the period). A decrease occurred in 49 of those periods.
3) The largest increase in the SPX during a single period was 11.15% from 9/21/2001 to 10/19/2001. The average VIX during this period was 33.78.
5) The largest decrease in the SPX during a single period was 16.88% from 8/17/2001 to 9/21/2001 (the period preceding the largest increase!). The average VIX during this period was 28.94.
6) For the 61 periods that the SPX was higher at the end of the period than at the beginning, here are approximate ranges:
8 times the %change in the SPX was less than 1%
6 times the %change in the SPX was between 1% and 2%
26 times the %change in the SPX was between 2% and 5%
21 times the %change in the SPX was greater than 5%
7) For the 49 periods that the SPX was lower at the end of the period than at the beginning, here are approximate ranges:
13 times the %change in the SPX was less than 1%
11 times the %change in the SPX was between 1% and 2%
13 times the %change in the SPX was between 2% and 5%
12 times the %change in the SPX was greater than 5%
Wow! 1/3rd of the time that the SPX increased it increased by 5% or more.