SPDR S&P 500 (SPY)

The oldest and largest U.S.-listed exchange traded fund, SPDR S&P 500 (NYSEArca: SPY), will turn 20 years old later this month after the overall ETF business saw record inflows for 2012.

The $133 billion ETF was launched on Jan. 22, 1993, according to manager State Street Global Advisors.

The S&P 500 portfolio ushered in a revolution in investing as total ETF assets in the U.S. have ballooned to nearly $1.4 trillion.

“ETFs now account for 13% of total ETF and mutual fund assets, excluding money market funds,” reports Morningstar analyst Michael Rawson. “ETF assets have more than doubled since the end of 2008, in part due to particularly strong flows into fixed-income ETFs. Taxable bond ETF assets hit $225 billion up from $53 billion four years ago.”