Exchange-traded funds (or ETFs) are Open Ended investment companies that can be traded at any time throughout the course of the day. Typically, ETFs try to replicate a
stock market index such as the
S&P 500 (e.g.
SPY) or the
Hang Seng Index, a
market sector such as energy or technology, or a
commodity such as
gold or
petroleum; However, as ETFs proliferated in 2006 from under one hundred in number to almost four hundred by the end of the year, the trend has been away from these simpler index-tracking funds to
Intellidexes and other proprietary groupings of stocks.
See more at Wikipedia.org...