The value of assets invested in US exchange-traded funds hit a record high of $1.1bn at the end of August, according to new research, as investors "tactically" adjusted to the S&P’s rally.

The rise in assets through August marks the second month of consecutive asset growth for the products, according to data from independent research and consultancy firm ETFGI. It follows a three month slump from April to June that was largely the result of market declines that weighed on the value of assets.