its a very slick method of active management.
traditional mutual funds have to be wary of fund flows....need to have cash on hand for redemptions.
ETF wrapper, the fund manager simply manages the portfolio with no regard to fund flows...allows them the freedom to truly manage the portfolio.
This is why Jim Cramer looked like a fool the other day when he said "close the fund". you can't close an etf to new investors like traditional mutual funds or hedge funds, nor can you limit redemption period or schedule. and the inflows or outflows really have no influence on the fund manager and their mgmt style. they post the trades they make and the market makers/authorized participants follow the same investment allocation.
really slick.
great wiki link by the way.
4th edit. see how the big index ETFs like SPY, VTI, IVV, VOO, QQQ etc....the big ones, see how this makes them more efficient and harder to beat by active managers, they don't have fund flows to contend with. Thats up to the market makers/participants.