The first ETF launched 30 years ago, revolutionizing investing

Thirty years ago, the launch of the first exchange-traded fund ushered in a new era of investing. Now, the industry is bringing exotic trading strategies to the masses.

The SPDR S&P 500 ETF Trust, which tracks the benchmark U.S. stock index, gave investors the ability to buy and sell hundreds of stocks through a single, publicly traded share for the fir