The exchange-traded fund (ETF) industry is in full bloom now.
According to ETF Central, a platform that tracks ETF markets and issuer data, there were more than 5,500 U.S.-listed ETFs as of July 23. That's explosive growth compared with January 22, 1993, when the first U.S.-listed ETF, the SPDR S&P 500 Trust (SPY), launched and kicked off the modern exchange-traded-fund era.