Option expiration week is often a pretty good week for the market. October is one of those months where it has been especially good over the years. This can be seen in the study below.

I decided to exclude 2008 because action that week was such an incredible outlier that it greatly skewed all the stats. (The week started with an 11.5% gain on Monday of 2008.) Even without 2008, results 1-4 days out look pretty solid.
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