When the SPDR S&P 500 Trust (SPY) was submitted to the SEC in 1988, George Michael’s "Faith" was the No. 1 song and Magic Johnson led the Lakers to another NBA Championship. By the time SPY finally launched in 1993, Nirvana had ushered in the grunge era and Michael Jordan had taken over the NBA. While the SEC wrestled with this unique product -- which was almost like a foreign object that had landed on their desks -- the whole culture had changed.

In those four long years, there was much back and forth between the SEC and the SPY teams over logistics, structure, and the creation-redemption process, which was inspired by commodities warehouses. The patience and labor paid off for the ETF's creators, who figured out how to keep fees low and also earn some unintended windfalls, such as the products’ tax efficiency.