I think an addition to the liquidity point: Once something becomes "common knowledge" in the stock market, it looses all predictive power. In this example, yo

I think an addition to the liquidity point: Once something becomes "common knowledge" in the stock market, it looses all predictive power. In this example, you could trade on the index inclusion because it observably happened, but market participants didn't respond. Now, everyone expects the effect to happen, so it's just another thing 'baked in' to pricing.