Exchange-traded funds added $22.36 billion in August, driving total ETF assets to $1.215 trillion, according to data from the Investment Company Institute. Over the past 12 months, ETF assets increased $173.89 billion, or 16.7%.

Assets in domestic equity ETFs increased $106.14 billion since August 2011, and global equity ETFs assets rose $4.17 billion during this period.

Also, assets of bond funds were $229.57 billion and hybrid funds were $512 million at the end of August.