The exchange traded fund industry is going mainstream, with prime time commercial advertisement spots and recognition by most individual investors. As the number of ETFs trading keeps growing and the assets under management keep multiplying, many are calling this time an “ETF boom.”

“As we approach the halfway point of 2012, we are on track for yet another period of tremendous growth for the line up of ETFs. More than a hundred new funds have begun trading already this year, and dozens of issuers continue to plan aggressive expansions of their product lineups,” Michael Johnston for ETFdb.com wrote. [Why Institutional Investors are Using ETFs More]

According to the ETF Industry Association, at the end of May, ETFs accounted for more than $1.14 trillion, an increase of 2% from the month before. There are now 1,465 ETF products trading, up from 1,254 one year ago, reports David Francis for US News.

Institutional investors have been keen on ETFs for some time. It has become apparent that ETF providers are now targeting individual retail investors. The ETF has become an important asset allocation tool, but only for those that really understand how they work and what they are tracking. [The 10 Best Selling ETFs of 2012]