The trillion-dollar ETF boom triggered by the financial crisis 

One of the biggest stories to come out of the financial crisis is the rise in exchange-traded funds. In 2008 U.S. investors had $531 billion in ETFs; that’s jumped to more than $3.4 trillion today.
— Read on www.cnbc.com/2018/09/14/the-trillion-dollar-etf-boom-triggered-by-the-financial-crisis.html