Q: SPHQ ETF seems to have a good long term total return performance compared to SPY. When I looked in more detail it looks like Invesco changed the index 3 times since it's December 6, 2005 inception date. I'm trying to validate the active strategy but it's seems difficult to make any assumptions. Is it common for ETF providers to change underlying indexes? I looked at other Invesco ETF's and it seems like they in particular do it for some of there other ETF's as well. I would appreciate your thoughts.

Q: The rise in stock prices of a few mega-caps (Apple, Facebook, Amazon, etc.) has distorted the concept of broad diversification through index investing (S&P 500). While the index rises, many index constituents have performed poorly.

Some ETF providers have created funds that hold a subset of the components of existing indices. Inclusion is based on their concept of company "quality". Presumably this eliminates poor performers and results in a "better" fund.
Examples are: ZUQ, SPHQ, QUAL, ZGQ, ZEQ.

Please comment on this idea of "quality" subsets of existing indexes. Do you consider this to be a useful investing strategy? Would you consider the examples listed to be preferable investments compared to the broader indices?

Thank you.
IslandJohn