saw this over at minyanville.com and thought it might be of interest ...
"I wanted to quickly walk you through the process of an NDX rebalancing. Fifteen names in the NDX 100 are going to be removed and fifteen new names are going to take their place. Letâs say that the average price of the âdeletesâ is (for arguments sake) $1 and the average price of the âaddsâ is $5. In order to raise the money to pay that incremental $4, index funds will have to sell the other 70 (unaffected) names (the actual calculation is based on capitalization, not stock price, but you get the gist). I am hearing, and this purely conjecture and NOT actionable, that the sell pressure on the index (into tomorrowâs close) could be (up to) $750 million. Iâm not gaming it, mind you, but I wanted to be your ears on this one. " - Todd Harrison