As a small- to mid-cap investor, I can assure anyone pinning...

As a small- to mid-cap investor, I can assure anyone pinning their hopes on index inclusion that they will be sorely disappointed.
Most funds follow rules with sufficient flexibility that they can accumulate over a time period, often front- running the actual inclusion and then through a pretty long tale after that date. The effect of this is that there is no appreciable "spike" as all action is spread out and takes place according to much more sophisticated macro signals. Whilst I would view index inclusion as a positive, I would expect any SP rise to pretty much reflect regular operations.