>Correction: index funds don't have a choice. They must follow the index, and so must buy the stock.

Right, if they've advertised as an S&P 500 index fund, they have to robotically follow the S&P 500, stupid inclusions and all. Changing that strategy would require ... a lengthy process involving input from shareholders.

However, someone can still start e.g. a "classic S&P 500" fund that follows the old rules for inclusion, and I suspect we'll see that in response to these recent decision.