Oh man - just read Matt Levine's stuff: https://www.bloomberg.com/view/articles/2015-07-22/index-funds-may-work-a-little-too-well https://www.bloomberg.com/view

Oh man - just read Matt Levine's stuff: https://www.bloomberg.com/view/articles/2015-07-22/index-funds-may-work-a-little-too-well https://www.bloomberg.com/view/articles/2015-07-22/index-fun... Good question - this is an on-going topic in the market actually. The correct answer, like a lot of financial economic theory goes, is that no one actually really knows.