State Street reported that as of August 31, there were 710 exchange traded funds available in the U.S. offered by 24 ETF managers; two new individual ETFs were launched in August, State Street reported, and one new manager joined the fray. ETF industry assets grew $4.7 billion in August to reach a total of approximately $582 billion.

By contrast, the Investment Company Institute reported at the end of July that total assets in the nation’s 8,073 mutual funds decreased by $91.5 billion in the month to settle at $11.588 trillion.

Joining the growing list of ETF offerings is Invesco PowerShares Capital Management, which recently announced the listing of six new exchange traded funds, all of which are rebalanced quarterly using a modified cap-weighting methodology, and which are expected to be listed Sep. 18.

The six are: the PowerShares Global Biotech Portfolio (PBTQ), based on the Nasdaq OMX Global Biotech Index; the PowerShares Global Progressive Transportation Portfolio (PTRP), a green transportation fund based on the Wilder Nasdaq OMX Global Energy Efficient Transport Index; the PowerShares Global Agriculture Portfolio (PAGG), based on the Nasdaq OMX Global Agriculture Index; the PowerShares Global Coal Portfolio (PKOL), based on the Nasdaq OMX Global Coal Index; the PowerShares Global Gold and Precious Metals Portfolio (PSAU), based on the Nasdaq OMX Global Gold and Precious Metals Index; and the PowerShares Global Steel Portfolio (PSTL), based on the Nasdaq OMX Global Steel Index.