An Exchange-Traded Fund is a fund made up of a group of assets that can be purchased all at once (ie, without having to buy each component individually). Unlike mutual funds (which are only priced at the end of the trading day), ETFs can be bought and sold throughout the day. In practice, ETFs are a way traders or investors attempt to diversify a portfolio. In addition, they frequently have lower fees than other types of funds. EFTs represent a basket of stocks, such as cyber-security, communication, or even the S&P 500 itself.