Morningstar, in the report.There are 33 ETF providers in the U.S., but the top three firms account for 84% of the assets. [The Rich Get Richer in ETFs]Russell Investments is closing all its ETFs except one, and Scottrade???s FocusShares is exiting the business altogether. [ETF Closures Reveal Fierce Competition for Market Share]???It has never been easy to be in this business, but the challenges