Nielsen to be replace Sprint Nextel in S&P 500

[whatchamacallit]

http://finance.yahoo.com/news/nielsen-r ... 06336.html

What is this going to do to Sprint stock or Nielsen stock?

I am sure stocks swap out at the bottom all of the time but I have never paid attention before. Wouldn't dropping out of the index or getting added to the index cause a massive sell or buy?

I don't think I would risk buying either directly but I am just curious how the value could stay stable through this change.