$GOOG (3.2% of the the S&amp;P 500) and $FB (1.8%) together are 5.0% of the S&amp;P.

That is more than Utilities (3.4%), Real Estate (2.9%), Energy (2.7%), or Materials (2.4%). 

$SPY $IVV $XLU $XLRE $XLE $XLB