Homebuilder Lennar added to S&P 500 and then stock gets hit

This is an unusual post.Homebuilder Lennar was added to the S&P 500 as of Monday's close.When a stock is added to the index all those mutual funds and pension funds that mimick the index are forced to buy the new addition thus providing huge demand for the stock.Look at Lennar the last couple of days.This could be a signal that some are cooling on the homebuilder and real estate in general.For a stock to be down after added to the S&P 500 is news.