SandP 500 becomes SandP 5.  Portfolio weight of largest 5 companies in SandP 500 = “almost 23%”  Their weight 5 years ago = “less than 10%”  FT, June 15, p.18 $spx, $spy  (A 1% stock price move in these 5 now moves the Index 2.3 times more than 5 years ago.)