[dotnetchris]

Much riskier proposition because you have no idea of the timeframe of WHEN their positions will be divested. Your margin might get called before it happens and you lose or lose alot. With the long position buying the stock prior to its entry to the index you have a much more reliable indicator that you'll make profit.

Honestly the simplest thing to do is just monitor the big houses and whatever they do en masse do the same. Most giant purchases have to be announced and 10M shares aren't just bought on a whim.