I looked at the run-up before Windows 95, 98, XP and now Vista. I ignored the updates. Also, there is a distortion in the data from the unfortunate events of 9/11. Lastly, I am using November 15, 2006 (middle of the month) since I do not know the actual release date of Vista. And, of course, I do not have the 6 month data for the Vista release.
In addition to the run-up, I also put in the return of the stock the following 3 months to see if the operating software release had any lasting effect. As you can see from the chart, the 90’s provided tremendous returns. Post release returns in 2 out of the 3 cases have been higher as there has been follow through in the following 3 months.