The $127 billion SPDR S&P 500 ETF (NYSEArca: SPY) is celebrating its 20th birthday on Tuesday. The first U.S. exchange traded fund — which listed on Jan. 29, 1993 – is the most traded equity security in the world.

“Looking back on these 20 years, it’s pretty amazing the impact that SPY and ETFs in general have had on the investment community, investors and financial advisors,” said Jim Ross, global head of the ETF business at State Street Global Advisors, in a telephone interview. “ETFs have changed the way stocks trade and changed the way people look at the market and diversification.” [SPDR S&P 500 Marks Two Decades of ETF Growth]

The State Street executive also pointed out that ETFs have created thousands of jobs in the financial industry

Ross was at the New York Stock Exchange on Tuesday to help ring the closing bell and mark SPY’s 20th anniversary. He also serves as chairman of the ETF committee at the Investment Company Institute.

The launch of SPY, known as “Spiders” among traders, in the early 1990s was the opening salvo of a revolution in markets and investing. ETFs are baskets of securities that started out as index funds that could be traded in real time. They are known for their low costs, tax efficiency and liquidity. The financial products let investors buy entire segments of the equity, bond and commodity markets with one trade. ETFs have also branched out to other areas such as currencies and active strategies. [SPDR S&P 500 Eyes 20th Birthday After Record ETF Flows]