The Two Stock Indexes All ETF Investors Should Know

There are hundreds of exchange traded funds (ETFs) out there to represent almost any conceivable theme or index. But two indexes in particular are the most widely watched in the world, and any ETF investor should be familiar with them.

The Dow Jones Industrial Average has the Diamonds Trust (DIA: 100.19 -0.33 -0.33%) while the S&P500 has the SPDR S&P 500 (SPY: 106.61 -0.40 -0.37%). FinWeb says that these are the two most widely watched stock indexes in the United States, making them worth your time to watch, as well.

• Diamonds (NYSEArca: DIA): The Dow Jones Industrial Average is made up of of 30 large-cap stocks that are thought to represent the broad market. Most retail investors watch this index, and it is the one you will be most likely to hear referred to by the popular press. DIA is very liquid, trading over 10 million shares per day on average.

• SDPR S&P 500 (NYSEArca: SPY): The S&P 500 is made up of 500 of the largest companies that are publicly traded in the United States. This is the index that is most watched by professional traders, so if this makes a difference to you, SPY would be a better option than DIA. This index is more of an indicator of the broad market, as professional traders are driving it. SPYs are extremely liquid, currently averaging more than 166 million shares per day.